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Background: Exposing blood specimens to air reduces plasma total carbon dioxide (TCO 2 ). We evaluated the degree of TCO 2 reduction attributed to open collection of neonatal blood in BD microtainers® (microtainers), microtainer transport duration and delayed testing of open plasma aliquots., Methods: Venous blood was aliquoted into open microtainers in a 3x4 factorial design to simulate combined effects of blood volume (0.2-0.6 mL) and air exposure duration (0-5 min), with blood drawn in vacutainers as a control. Separate effects of in-hospital transport duration (0-120 min; whole blood), off-site transport duration (0-24 h; centrifuged whole blood), and the duration plasma aliquots remained open (0-120 min) were evaluated by repeated testing. Findings were analyzed using repeated-measures ANOVA and Student's T-tests., Results: In the factorial experiment, mean plasma TCO 2 in microtainers was on average 3.5 mmol/L lower than in vacutainers. Smaller blood volume but not greater air exposure duration significantly (p < 0.05) reduced TCO 2 . Mean TCO 2 in filled (0.6 mL; 1-5 min air exposure) microtainers was on average 2.9 mmol/L lower than in vacutainers. Simulated off-site transport of microtainers containing centrifuged whole blood significantly reduced TCO 2 (4 h; mean change = -1.5 mmol/L), as did delayed testing of aliquoted plasma (15 min; mean change = -1.3 mmol/L)., Conclusions: Plasma TCO 2 decreased with reduced microtainer blood volume, extended off-site transport duration of centrifuged whole blood and testing delay of aliquoted plasma. To minimize TCO 2 reduction, microtainers should be fully filled and tested rapidly. Laboratories should also consider whether an interpretive comment, correction factor or separate reference intervals are appropriate for these tests., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Minimizing hemolysis during phlebotomy ensures accurate chemistry results and reduces test cancellations and specimen recollections. We developed videos demonstrating best practices to reduce hemolysis and tested whether distribution to clinical nurse educators (CNEs) for provision to nursing staff affected the degree of specimen hemolysis in hospital inpatient units and outpatient clinics., Methods: Videos of common blood collections demonstrating best practices to reduce hemolysis were filmed and then distributed via email link to all hospital-based CNEs in Calgary, Alberta, Canada. (https://vimeo.com/user18866730/review/159869683/a0cec9827f). Roche Cobas hemolysis index (H-index) results from specimens collected +/- 12 months from the date of video distribution were extracted from Roche Cobas IT middleware (cITM) and linked to collection location. An interrupted time series (ITS) analysis with collection location as the unit of anlaysis was used to quantify impact of video distribution on the trajectory of weekly mean log-H-index weighted by inverse variance., Results: In +/- 3 months of data flanking video distribution (n = 137 241 collections), where overall impact was strongest, H-index trajectory (change in units per week) decreased immediately following video distribution (-5.7% / week, p < 0.01). This was accompanied by a 22% drop in overall H-index from the week before to the week after video distribution (y-intercept change, or gap). There was also a small but significant overall decrease in the proportion of hemolyzed specimens (-0.3%, p < 0.01). These changes were not observed at all collection locations, and in fact increases occured at some locations., Conclusions: We developed a novel and convenient educational aid that, when distributed, was associated with beneficial changes in specimen hemolysis at hospital inpatient units and outpatient clinics. Including it in ongoing nursing education will fill a knowledge gap that may help to reduce specimen hemolysis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Introduction: The use of dried capillary microsamples for clinical chemistry testing is an interesting alternative to conventional phlebotomy. Sampling devices capable to produce plasma from whole blood application are particularly useful. The aim of this study was to validate theHealthID PSDmicrosampling device for the determination of cholesterol (CHOL), high-density lipoprotein (HDL), triglycerides (TRIG), creatinine (CRE), and glycated hemoglobin (HbA 1 c) after collection of capillary blood., Methods: Dried blood and plasma extracts were analyzed using modified methods in an open-channel biochemistry analyzer. The plasma volume in the extracts was corrected by the concentration of chloride (CL). Linearity, imprecision, bias, stability, and comparability to conventional samples were evaluated., Results: Dried plasma assays presented total error (TE) within acceptable limits. The analytes were stable for up to 14 days at 40 °C. Predicted serum concentrations of CHO, HDL, TRI, and CRE and predicted whole blood levels of HbA 1 c, using dried extracts measurements, did not presented systematic or proportional differences to serum and whole blood levels., Conclusions: Dried sample extracts obtained with capillary blood applied to the HealthID PSD allowed the determination of CHO, HDL, TRI, CRE, and HbA 1 c, as well as the calculation of LDL level, using only 5 drops of blood. This sampling strategy can be useful for population screening programs, particularly in Developing Countries., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: The authors of the manuscript disclose the following: G.L. is an employee of HealthID Lab; M.F.C. and R.L. have stock ownership in HealthID Lab., (Copyright © 2023 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Background: Frequent blood phenylalanine (Phe) measurement is required for phenylketonuria (PKU) patients for diagnosis and disease status monitoring. Though various methods are available for blood Phe measurement, there is a lack of validated quantitative methods for measuring Phe with less than 15% variability. A method to allow at home blood sample collection for the PKU community is in high demand., Methods: A volumetric absorptive microsampling (VAMS) dried blood collection high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and fully validated for blood Phe measurement in compliance with regulatory guidances. The method accuracy, precision, stability, selectivity, matrix and hematocrit effects were assessed. A venous plasma collection HPLC-MS/MS method was developed and validated as a reference method. 311 matching VAMS and plasma samples were collected from 24 PKU subjects in a Phase 2 clinical study. Phe measurements using the two methods were compared., Results: Both VAMS and the plasma sample collection methods met the acceptance criteria for Good Laboratory Practice (GLP) bioanalytical analysis. Comparisons showed a high Pearson's correlation of 0.9813. The Passing-Bablok analysis showed that the difference was estimated to be less than 5% and Bland Altman analysis indicated that the difference was proportional with Phe concentration and for the majority of samples (88.85%) the measurement was within ±20% difference. Following 7 days treatment with 60 or 20 mg/kg/day PTC923 (Sepiapterin) or 20 mg/kg/day sapropterin, PKU patients exhibited respectively -206.4, -146.9, and -91.5 µmol/L reductions of blood Phe as measured by the VAMS method., Conclusions: Concordant results were obtained using VAMS and plasma methods, which demonstrated that VAMS is a reliable method for clinical applications to monitor blood Phe for PKU patients., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The preanalytical phase of testing, including sample transportation, is a common source of error in laboratory testing. Previous studies have shown inversion of centrifuged plasma separator tubes (PST) results in elevation in certain analytes. However, it remains unclear if routine transportation practices, without full inversion, can have a similar impact. This study used 12 residual samples submitted in PST and 4 PST tube samples collected from healthy donors. All samples were measured at baseline. Analytes measured were white blood cells (WBCs), red blood cells (RBCs), platelets (PLTs) using the Sysmex XN-1000 and potassium (K), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), sodium (NA), and alanine aminotransferase (ALT) using the Ortho Vitros 4600. The samples were split into two groups: 1 group was placed vertically in racks and the other group were laid horizontally in a messenger bag-style soft-sided cooler used by lab couriers. A cold pack was placed in the bag, equidistant from both groups of samples. To mimic courier transportation, the bag was carried for 30 min, returned to the laboratory and immediately analyzed. Subsequently, the samples were re-centrifuged and analyzed again. Statistics were performed using GraphPad Prism. LDH increased following transportation for vertical and horizontal samples and remained elevated despite re-centrifugation. K was only increased in the horizontal samples following re-centrifugation. Notably, AST as well as WBCs, RBCs, and PLTs all increased following transportation, but dropped to baseline concentrations following re-centrifugation. Centrifuged PSTs should be kept in a vertical position during transportation by courier. Re-centrifugation of plasma gel tubes after transportation may be necessary for certain chemistry tests., (Copyright © 2022 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objective: The BD Vacutainer® Barricor™ plasma blood collection tube uses a mechanical separator during centrifugation to separate plasma from the cellular elements of blood. Compared to use of plasma separator tubes (PST™) with gel, Barricor™ produces a cleaner sample with less residual cellular content. We sought to determine if Barricor™ reduces pre-analytical error compared to PST™., Design & Methods: We used a model previously published that utilizes serial differences between intra-patient measurements transformed into a Taylor series of variation vs time with the y-intercept equal to the sum of short-term analytic variation, preanalytic variation and biologic variation. The intra-patient variation of chloride, sodium, potassium, and troponin-T (hs-TnT) obtained from the Emergency Department of a large tertiary care center sampled with PST™ (May 2015-April 2018, n = 59,762 specimens) or Barricor™ (May 2018-May 2021, n = 61,512 specimens) was evaluated. All specimens were analyzed on either Roche Modular or Cobas® instruments. For each analyte, pairs of intra-patient results were tabulated and separated by 1 h intervals. The average between-pair variations were then regressed against time. We also determined the number of intra-patient outliers using the reference change value for each analyte., Results: The Barricor™ hs-TnT y-intercept (-0.0132) was significantly lower than the PST™ intercept (0.9109; p = 0.022). This was also true for chloride (y-intercept = 1.0067 in Barricor™ and 1.3431 in PST™, p = 0.037). The percentage of hs-TnT outliers was significantly lower in Barricor™ (8.32 %) vs PST™ (12.2 %; p < 0.001)., Conclusion: The analytical and biological variations are assumed to be steady over the study periods; we ascribe the difference in the y-intercept to the preanalytical effect of the Barricor™ tube reducing platelets and other cellular debris., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

Background: Pediatric cancer patients undergoing chemotherapy or radiation therapy generally require a central venous catheter (CVC). However, serum drawn from CVCs has several drawbacks for use in routine chemistry tests. Biochemical analytes were evaluated using heparin plasma instead of serum to maintain turnaround time and to prevent problems caused by micro-clot formation or delayed clotting time., Methods: Venous blood samples from 52 pediatric oncology patients with chemoports or Hickman catheters were collected in serum separating tubes (SSTs) and lithium heparin tubes (LHTs). A total of 29 parameters were analyzed on a Cobas c702 (Roche Diagnostics, Mannheim, Germany). Passing-Bablok regression and Bland-Altman difference plots were used for statistical analyses., Results: When the mean value of each analyte measured from LHT was compared with those from SST, percentage bias was within the desirable bias limit in most of the analytes. However, albumin, potassium, and inorganic phosphorus showed a negative constant bias of -3.0%, -5.3%, and -1.6%, respectively, and total protein showed a positive constant bias of + 3.8%., Conclusions: The use of LHTs for sample collection from pediatric patients with CVCs could be helpful for routine chemistry analyses. The results of potassium and total protein should be interpreted with consideration of the difference between serum and plasma samples., (Copyright © 2022. Published by Elsevier Inc.)

Background: Serial monitoring of tacrolimus and serum creatinine after renal transplantation is of vital importance. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the estimation of tacrolimus and creatinine, obtained from dried blood spots (DBS) or by volumetric absorptive microsampling (VAMS) was validated and the two sampling strategies were compared with traditional venous sampling., Methods: The LC-MS/MS assay was validated using a shared extract for the estimation of tacrolimus and creatinine from DBS and VAMS independently. The relationship between the concentrations in DBS/VAMS specimens and in venous samples was assessed using Passing-Bablok (PB) analysis and the bias between the two methods was determined by the Bland Altman (BA) analysis., Results: The imprecision and bias of tacrolimus and creatinine estimated from DBS and VAMS samples was <12% and was independent of the hematocrit (Hct). Samples were stable for five days at ambient temperature. From the PB regression analysis, correction equations were generated for the prediction of tacrolimus and creatinine values from DBS and VAMS samples. In a separate cohort of patients for validation, the corrected DBS and VAMS concentrations had a mean (95% CI) bias for tacrolimus of -0.64 (-2.98 to 1.70)% and -0.92 (-3.69 to 1.85)% respectively and for creatinine of 1.00 (-2.73 to 4.72)% and -0.71 (-3.74 to 2.32)% respectively. Using DBS and VAMS respectively, for tacrolimus, 91.8 and 89.8% of patient values and for creatinine, 69.4 and 81.6% of patient values were within the limits of clinical acceptance (within 15% agreement against the venous samples)., Conclusion: We conclude that VAMS is the preferred single sampling option for estimating tacrolimus and creatinine in renal transplant patients., (Copyright © 2022 The Canadian Society of Clinical Chemists. All rights reserved.)

Introduction: The type of blood collection tube used when obtaining samples for therapeutic drug monitoring (TDM) has important implications on the accuracy of results. Serum tubes without a gel separator are currently considered best practice. We sought to evaluate the performance of Barricor™, a novel plasma tube that utilizes an inert mechanical separator, as well as a gel-based tube (PST™) for testing acetaminophen, digoxin, gentamicin, methotrexate, phenobarbital, phenytoin, salicylate, vancomycin, valproic acid, carbamazepine, and theophylline on a Roche Cobas® 8000 platform., Methods: Paired patient samples were collected from individuals taking at least one of the medications evaluated. These were supplemented with spiked specimens to ensure a minimum of 40 paired samples per drug. All drugs were measured within two hours of collection on Roche e602 or c502 instruments. Deming regression was used to assess bias between Barricor™ vs serum and PST™ vs serum. Seven-day refrigerated stability was also assessed in Barricor™, PST™, and serum tubes in a subset of samples (n = 10) for each drug., Results: Drug concentrations in Barricor™ were similar to serum for each drug assessed. In contrast, a negative bias was observed in PST™ compared to serum tubes for carbamazepine (-7.6%) and phenytoin (-6.8%) although this did not surpass our total allowable error goal of 10%. All drugs recovered within ±10% of baseline value when samples were stored refrigerated for 7 days except for carbamazepine, phenytoin, and phenobarbital where significant analyte loss was observed within the first day in PST™ tubes., Conclusion: Barricor™ tubes are a suitable alternative to serum for TDM on the Roche Cobas® 8000 platform., (Copyright © 2021 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: Camostat mesilate is a drug that is being repurposed for new applications such as that against COVID-19 and prostate cancer. This induces a need for the development of an analytical method for the quantification of camostat and its metabolites in plasma samples. Camostat is, however, very unstable in whole blood and plasma due to its two ester bonds. The molecule is readily hydrolysed by esterases to 4-(4-guanidinobenzoyloxy)phenylacetic acid (GBPA) and further to 4-guanidinobenzoic acid (GBA). For reliable quantification of camostat, a technique is required that can instantly inhibit esterases when blood samples are collected., Design and Methods: An ultra-high-performance liquid chromatography-tandem mass spectrometry method (UHPLC-ESI-MS/MS) using stable isotopically labelled analogues as internal standards was developed and validated. Different esterase inhibitors were tested for their ability to stop the hydrolysis of camostat ester bonds., Results: Both diisopropylfluorophosphate (DFP) and paraoxon were discovered as efficient inhibitors of camostat metabolism at 10 mM concentrations. No significant changes in camostat and GBPA concentrations were observed in fluoride-citrate-DFP/paraoxon-preserved plasma after 24 h of storage at room temperature or 4 months of storage at -20 °C and -80 °C. The lower limits of quantification were 0.1 ng/mL for camostat and GBPA and 0.2 ng/mL for GBA. The mean true extraction recoveries were greater than 90%. The relative intra-laboratory reproducibility standard deviations were at a maximum of 8% at concentrations of 1-800 ng/mL. The trueness expressed as the relative bias of the test results was within ±3% at concentrations of 1-800 ng/mL., Conclusions: A methodology was developed that preserves camostat and GBPA in plasma samples and provides accurate and sensitive quantification of camostat, GBPA and GBA by UHPLC-MS/MS., (Copyright © 2021 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Preanalytical hemolysis of blood samples is a common problem in medical practice, especially in emergency departments. Several potential influences on sample hemolysis have been investigated, including sampling techniques, centrifugation and sample transport. In particular, the use of intravenous catheters and the vacuum sampling technique have often been demonstrated to provoke hemolysis. Other factors playing a role include the use of inappropriate puncture sites, complicated blood sampling, prolonged tourniquet application, underfilling of tubes and excessive shaking of specimens. Training of phlebotomists can play a pivotal role in overcoming these issues. A sample may also undergo hemolysis at the point of centrifugation, more specifically when centrifugation lasts too long or is done repeatedly. Pneumatic tube system (PTS)-transported samples tend to be more strongly affected by hemolysis compared to hand-carried ones, though whether this difference is clinically relevant remains questionable. The velocity at which the sample moves, the distance it covers and the shock forces it sustains all determine to what extent hemolysis occurs during PTS transport. The use of cushion inserts in the carrier to stabilize the samples and the presence of a gel separator in the transported serum tubes may prevent PTS-induced hemolysis. Finally, there is considerable variation between patients in the extent to which samples are prone to hemolysis. Sample hemolysis leads to unreliable laboratory results, delayed diagnosis and patients suffering avoidable discomfort. Specifically, hemolysis may interfere with laboratory results due to release of intracellular components, dilution effects, proteolysis and interference with analytical techniques. There is ongoing debate about how laboratories should deal with results altered by hemolysis. Laboratory specialists should clearly communicate with the ordering clinicians in order to make an informed decision about how to interpret hemolysis-affected analytical results. This review looks into current evidence concerning the causes and consequences of in vitro hemolysis, and aims to explain how to deal with it., (Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: BD Canada recently released a blood collection tube with a novel mechanical separator called the Barricor. We evaluated this tube as an alternate sample type for cardiac troponin I (cTnI) testing using the Beckman Coulter AccuTnI+3 assay., Design and Methods: 3014 paired patient specimens (Barricor, plasma separator tube or PST) were obtained from the emergency departments and cardiac care units of nine hospitals in and around Edmonton, Alberta. After centrifugation, each plasma sample was analyzed for cTnI using the Beckman Coulter AccuTnI+3 assay. In addition, selected samples were analyzed multiple times within a single run or over 4-5days to generate imprecision data for the assay., Results: Repeatability and within-laboratory studies revealed an imprecision of <10% at concentrations above 0.025μg/L for the Barricor as well as BD's traditional PST. Paired patient sample comparisons over the full range of the assay yielded linear regression slopes ranging from 0.956 to 1.011 and Pearson correlation coefficients ranging from 0.993 to 0.999. At a lower range of results closer to the manufacturer's 99th percentile cutoffs correlation was slightly worse, but still acceptable, with linear regression slopes ranging from 0.967 to 1.211 and Pearson correlation coefficients ranging from 0.983 to 0.987. Notably, at these lower concentrations the agreement between individual PST and Barricor results worsened with decreasing cTnI concentration. Differences between pairs of results became particularly large (-50 to +400%) at PST cTnI concentrations ≤0.015μg/L. Closer inspection of the data around the 0.02 and 0.04μg/L 99th percentile cutoffs revealed a number of discordances between PST and Barricor results, with at least some of these attributable to false elevations in the PST results., Conclusions: Together, our results suggest that the Barricor blood collection tube is good alternative to the traditional PST for cTnI testing using the AccuTnI+3 assay. The Barricor appears to minimize spurious, nonreproducible, and false elevations in cTnI results for a subset of patients but additional studies are needed to determine if it reduces overall false elevations. cTnI results below 0.04μg/L may still be of questionable accuracy even with the use of this new tube., (Copyright © 2017 The Canadian Society of Clinical Chemists. All rights reserved.)

The extra-analytical phases of the total testing process have substantial impact on managed care, as well as an inherent high risk of vulnerability to errors which is often greater than that of the analytical phase. The collection of biological samples is a crucial preanalytical activity. Problems or errors occurring shortly before, or soon after, this preanalytical step may impair sample quality and characteristics, or else modify the final results of testing. The standardization of fasting requirements, rest, patient position and psychological state of the patient are therefore crucial for mitigating the impact of preanalytical variability. Moreover, the quality of materials used for collecting specimens, along with their compatibility, can guarantee sample quality and persistence of chemical and physical characteristics of the analytes over time, so safeguarding the reliability of testing. Appropriate techniques and sampling procedures are effective to prevent problems such as hemolysis, undue clotting in the blood tube, draw of insufficient sample volume and modification of analyte concentration. An accurate identification of both patient and blood samples is a key priority as for other healthcare activities. Good laboratory practice and appropriate training of operators, by specifically targeting collection of biological samples, blood in particular, may greatly improve this issue, thus lowering the risk of errors and their adverse clinical consequences. The implementation of a simple and rapid check-list, including verification of blood collection devices, patient preparation and sampling techniques, was found to be effective for enhancing sample quality and reducing some preanalytical errors associated with these procedures. The use of this tool, along with implementation of objective and standardized systems for detecting non-conformities related to unsuitable samples, can be helpful for standardizing preanalytical activities and improving the quality of laboratory diagnostics, ultimately helping to reaffirm a "preanalytical" culture founded on knowledge and real risk perception., (Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

The use of liquid chromatography-mass spectrometry (LC-MS) for both diagnostics and research purposes is rapidly growing in clinical laboratories. As for more conventional areas of in vitro diagnostic testing, many preanalytical variables have an impact on these techniques and may hence jeopardize the quality of tests results. The leading preanalytical variables include patient preparation, the nature of the blood collection tubes and additives, interference from spurious hemolysis, sample handling and management, composition of blood tubes, contamination, as well as storage conditions. Therefore, the aim of this article is provide a narrative overview about the leading preanalytical issues which may ultimately influence LC-MS testing of human blood samples, and provide tentative indications, as for current evidence, about optimal preanalytical management of blood samples for proteomics and metabolomics studies. These general recommendations entail pre-storage centrifugation, use of appropriate tubes and additives, addition of bacteriostatic preservatives, enrichment and purification of samples, elimination of unsuitable specimens, rapid analysis or immediate storage at -70°C, and avoidance of analyzing frozen-thawed specimens., (Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

The measurement of plasma glucose (PG) plays a central role in recognizing disturbances in carbohydrate metabolism, with established decision limits that are globally accepted. This requires that PG results are reliable and unequivocally valid no matter where they are obtained. To control the pre-analytical variability of PG and prevent in vitro glycolysis, the use of citrate as rapidly effective glycolysis inhibitor has been proposed. However, the commercial availability of several tubes with studies showing different performance has created confusion among users. Moreover, and more importantly, studies have shown that tubes promptly inhibiting glycolysis give PG results that are significantly higher than tubes containing sodium fluoride only, used in the majority of studies generating the current PG cut-points, with a different clinical classification of subjects. From the analytical point of view, to be equivalent among different measuring systems, PG results should be traceable to a recognized higher-order reference via the implementation of an unbroken metrological hierarchy. In doing this, it is important that manufacturers of measuring systems consider the uncertainty accumulated through the different steps of the selected traceability chain. In particular, PG results should fulfil analytical performance specifications defined to fit the intended clinical application. Since PG has tight homeostatic control, its biological variability may be used to define these limits. Alternatively, given the central diagnostic role of the analyte, an outcome model showing the impact of analytical performance of test on clinical classifications of subjects can be used. Using these specifications, performance assessment studies employing commutable control materials with values assigned by reference procedure have shown that the quality of PG measurements is often far from desirable and that problems are exacerbated using point-of-care devices., (Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: Physical exercise up-regulates brain-derived neurotrophic factor (BDNF) in the brain and blood. However, there is yet no consensus about the adequate blood processing conditions to standardize its assessment. We aimed to find a reliable blood sample processing method to determine changes in BDNF due to exercise., Design and Methods: Twelve healthy university students performed an incremental cycling test to exhaustion. At baseline, immediately after exercise, and 30 and 60 min of recovery, venous blood was drawn and processed under different conditions, i.e. whole blood, serum coagulated for 10 min and 24 h, total plasma, and platelet-free plasma. BDNF concentration was measured by ELISA., Results: Exercise increased BDNF in whole blood and in serum coagulated for 24 h when corrected by hemoconcentration. We did not find effects of exercise on BDNF in serum coagulated for 10 min or in plasma samples. Plasma shows heterogeneous BDNF values in response to exercise that are not prevented when platelets are eliminated while homogeneous BDNF levels were found in whole blood or serum coagulated for 24 hour samples., Conclusions: In exercise studies, BDNF levels should be adjusted by hemoconcentration. Our data highlight the importance of blood sample selection since the differences between each one affect significantly the BDNF factor changes due to exercise., (Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: The REasons for Geographic and Racial Differences in Stroke (REGARDS) study is a prospective cohort of 30,239 Americans in the contiguous United States; the first of this scale to use home visits to obtain, process, and ship biologic samples to a core laboratory. Pre-analytical factors resulting from this study design may affect the results of some laboratory assays. We investigated the impact of REGARDS processing on a variety of analytes., Design and Methods: In REGARDS, blood samples were processed in the field by technicians who were trained on standardized methods for phlebotomy and sample processing. Field processing included centrifugation using varying non-uniform equipment and shipping overnight on ice to the University of Vermont, where samples were re-centrifuged for 30,000 ×g-minutes and stored at -80 °C. We assessed the effects of REGARDS sample handling by processing split samples from 20 volunteers using either ideal procedures or simulated REGARDS procedures. Assays for 19 analytes for potential study in REGARDS were then run on both samples and results compared., Results: Spearman correlation coefficients for analytes measured in ideal versus REGARDS processed samples ranged from 0.11 to 1.0. Thirteen of 19 analytes were highly correlated (>0.75), but platelet proteins were more variable., Conclusions: Simulation of non-optimal field processing and shipment to a central laboratory showed high variability in analytes released by platelets. The majority of other analytes produced valid results, but platelet contamination in REGARDS samples makes measurement of platelet proteins unadvisable in these samples. Future analytes considered by REGARDS or similar studies should undergo similar pilot testing., (Copyright © 2014. Published by Elsevier Inc.)

Objectives: Gaucher disease (GD) diagnosis relies on the demonstration of deficient β-D-glucosidase (GBA) activity in cellular homogenates. Diagnosis process, however, can be delayed as (i) some GD symptoms are non-specific; and (ii) diagnostic tests are performed in specialized laboratories. These difficulties negatively impact on timely access of patients to therapy. GBA assay in dried blood spots (DBS) represents a method facilitating early identification of patients who will be finally diagnosed with gold standard assay of nucleated cells. Aim of this study is to investigate the DBS analytical performance compared with gold standard method., Design & Methods: A cross-sectional study started by comparing data of 50 DBS and 50 homogenate samples from the same subjects (25 known-GD and 25 controls). The subsequent phase examined 443 DBS samples. Along with these, 73 blood samples were sent for leukocyte separation and/or EBV-lymphoblast cell lines, and 1 skin biopsy for fibroblast cell lines. Overall the study included a total of 493 subjects., Results: While the results from this first validation group did not yield false positive/negative values, when the analysis was extended to 443 DBS, 14.4% (64 samples) of positive results was yielded. Among these, only 15 were confirmed as GD values with gold standard test. In addition, a thorough examination of some clinical data also revealed 2 false negative results which were confirmed by both enzymatic and molecular analyses., Conclusions: DBS test could be useful as screening method although with cautions, whereas the standardized GBA assay should remain the gold standard for laboratory diagnosis of Gaucher disease., (Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: To ascertain whether or not the change in blood collection tubes for plasma glucose from fluoride/oxalate to citrate/fluoride/EDTA has had an effect upon the glucose results., Methods: Plasma glucose results from fasting patients from 2007 to 2012 were extracted from the laboratory information system. The data was evaluated in order to see the potential impact on patient results due to the change in glucose stabilizer implemented in September 2010., Results: The mean glucose result was increased by approximately 14% (difference: +0.80mmol/L) after the implementation of the citrate-buffered tubes (mean value=6.45mmol/L; n=15125) as compared to fluoride/oxalate tubes (mean value=5.65mmol/L; n=15867)., Conclusions: An increase in glucose results is seen after changing to citrate-buffered tubes due to the improved stabilizing effect as compared to fluoride. Properly collected blood samples will lead to the patient being correctly diagnosed. However, decision limits and reference intervals for glucose may need to be revised using citrate-tubes., (Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: This study was performed to establish the reference intervals for whole blood viscosity (WBV) using the analytical performance-evaluated scanning capillary tube viscometer (SCTV)., Design and Methods: The analytical performance of the SCTV was evaluated using three different levels of QC materials and sixty human EDTA-blood samples. To establish the reference intervals for WBV, 297 healthy individuals (123 men and 174 women) were selected from 1083 subjects., Results: Within-day precisions with QC materials and human whole blood and between-day precisions with QC materials were below 5.0%, 6.6% and 8.0% in CVs at all shear rates, respectively. Comparison tests between the SCTV and the Brookfield viscometer showed a significant correlation (R(2)=0.972, p<0.001). The reference intervals for WBV in healthy men were 3.66-5.41cP at 300s(-1) and 23.15-36.45cP at 1s(-1) while those in women were 3.27-4.32cP at 300s(-1) and 18.20-27.36cP at 1s(-1), respectively., Conclusions: Using the analytical performance-evaluated SCTV, the reference intervals for WBV were established in healthy adults, which could be beneficial to the clinical utility of WBV in the aspect of appropriate modalities for the improvement of blood viscosity., (Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: To study the ability of a stabilizing reagent to prevent cellular DNA contamination of cell-free DNA (cfDNA) in plasma during whole blood sample storage and shipping., Design and Methods: Samples were drawn from healthy donors into K₃EDTA and Cell-Free DNA BCTs (BCT) and stored at room temperature (RT). Aliquots were removed at specified time points and cfDNA was purified from the plasma. A Droplet Digital PCR (ddPCR) assay that amplifies a short β-actin gene fragment (136 bp) was used to measure the total plasma cfDNA (pDNA) concentration while a longer β-actin fragment (420 bp) was used to quantify genomic DNA (gDNA). In a follow-up experiment, blood samples drawn into the same types of tubes were shipped round trip by overnight air before cfDNA was isolated and analyzed., Results: Blood stored in K₃EDTA tubes at RT showed increases in pDNA and gDNA concentrations over time. However, both pDNA and gDNA levels remained stable in BCT for at least seven days. On day 14, there was a 4.5-fold increase in pDNA in BCT as compared to >200-fold increase in K₃EDTA tubes. Likewise, gDNA increased <2-fold on day 14 in BCT as opposed to a 456-fold increase in K₃EDTA tubes. Similar results were observed after samples were shipped., Conclusions: Cell-Free DNA BCTs prevent gDNA contamination that may occur due to nucleated cell disruption during sample storage and shipping. This novel blood collection tube provides a method for obtaining stable cfDNA samples for rare target detection and accurate analysis while mitigating the threat of gDNA contamination., (Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: Fetal mutations and fetal chromosomal abnormalities can be detected by molecular analysis of circulating cell free fetal DNA (ccffDNA) from maternal plasma. This comprehensive study was aimed to investigate and verify blood collection and blood shipping conditions that enable Noninvasive Prenatal Testing. Specifically, the impact of shipping and storage on the stability and concentration of circulating cell-free DNA (ccfDNA) in Streck® Cell-Free DNA™ Blood Collection Tubes (Streck BCTs, Streck, Omaha NE). These BCTs were designed to minimize cellular degradation, and thus effectively prevent dilution of fetal ccf DNA by maternal genomic DNA, was evaluated., Design and Methods: Peripheral venous maternal blood was collected into Streck BCTs to investigate four aspects of handling and processing conditions: (1) time from blood draw to plasma processing; (2) storage temperature; (3) mechanical stress; and (4) lot-to-lot tube variations., Results: Maternal blood stored in Streck BCTs for up to 7 days at ambient temperature provides stable concentrations of ccffDNA. The amount of fetal DNA did not change over a broad range of storage temperatures (4°C, 23°C, 37°C, 40°C), but the amount of total (largely maternal) DNA increased in samples stored at 23°C and above, indicating maternal cell degradation and genomic DNA release at elevated temperatures. Shipping maternal blood in Streck BCTs, did not affect sample quality., Conclusions: Maternal plasma DNA stabilized for 0 to 7 days in Streck BCTs can be used for non-invasive prenatal molecular applications, when temperatures are maintained within the broad parameters assessed in this study., (Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: There are no direct comparisons of blood glucose values in samples collected with barrier serum tubes (SST) and NaF/potassium oxalate (NaF/KOx) plasma tubes. Collection of samples in SST tubes can offer considerable savings and specimen processing advantages for national level surveys., Design and Methods: Serum and plasma samples were collected under 'field conditions' from a single draw of 3692 individuals participating in the Canadian Health Measures Survey. The samples were analyzed retrospectively using the VITROS GLU Slide method (glucose oxidase-based)., Results: There was a high rate of hemolysis in the NaF/KOx tubes (86.2%) while hemolysis was infrequently observed with the SST tubes (2%). Comparing only blood draws where no hemolysis was observed in both tubes (n=495; paired t-test) showed no effect of tube type on serum/plasma glucose concentrations. This was also observed when data was restricted to cases when only SST samples were not hemolyzed (n=3546; paired t-test)., Conclusions: These data show that both collection tubes can be used under survey collection and processing conditions to measure glucose with our assay system with no difference in reported results., (Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.)

Objective: To evaluate the effect of tubes mixing (gentle vs. vigorous) on diagnostic blood specimens collected in vacuum tube systems by venipuncture., Design and Methods: Blood was collected for routine coagulation, immunochemistry and hematological testing from one hundred volunteers into six vacuum tubes: two 3.6 mL vacuum tubes containing 0.4 mL of buffered sodium citrate (9NC) 0.109 mol/L: 3.2 W/V%; two 3.5 mL vacuum tubes with clot activator and gel separator; and two 3.0 mL vacuum tubes containing 5.9 mg K(2)EDTA (Terumo Europe, Belgium). Immediately after the venipuncture all vacuum tubes (each of one additive type) were processed through two different procedures: i) Standard: blood specimens in K(2)EDTA- or sodium citrate-vacuum tubes were gently inverted five times whereas the specimens in tubes with clot activator and gel separator were gently inverted ten times, as recommended by the manufacturer; ii) Vigorous mix: all blood specimens were shaken up vigorously during 3-5s independently of the additive type inside the tubes. The significance of the differences between samples was assessed by Student's t-test or Wilcoxon ranked-pairs test after checking for normality. The level of statistical significance was set at P<0.05., Results: No significant difference (P<0.05) was detected between the procedures for all tested parameters. Surprisingly only a visual alteration (presence of foam on the top) was shown by all the tubes mixed vigorously before centrifugation (Fig. 1 A, B and C). Moreover the serum tubes from vigorous mixing procedure shows a "blood ring" on the tube top after stopper removal (Fig. 1 D)., Conclusion: Our results drop out a paradigm suggesting that the incorrect primary blood tubes mixing promotes laboratory variability. We suggest that similar evaluation should be done using other brands of vacuum tubes by each laboratory manager., (Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: During the development of a testosterone assay by LC-MS/MS, we encountered significant assay interference introduced by blood collection tubes. We examined a number of commonly used blood collection tubes for the presence of interference and its impact on testosterone quantitation., Design and Methods: A number of commonly used blood collection tubes were examined by incubation of zero, low and high testosterone concentration samples with them over time, followed by sample preparation using liquid-liquid extraction and analysis by LC-MS/MS. Source of interference was identified by separately incubating blood collection tube coating, stopper and separator gel in clean glass tubes containing zero calibrator., Results: Significant interference was found in some blood collection tubes, with the separator gel identified as the main source. The magnitude of the interference increases over time and mainly affected one of the two testosterone mass transitions used in the quantitation, making it readily detected by the discrepant results obtained by each of the two testosterone mass transitions. We were unable to eliminate the interference by adjustment of the sample preparation procedure, and by changing LC or MS parameters. Accurate quantitation of testosterone is possible when the problematic tubes are avoided, and blood collection tubes free of interference are used instead., Conclusions: Significant LC-MS/MS testosterone assay interference that originated from certain type of blood collection tubes hampered testosterone analysis. Examination of blood collection tube and any other laboratory test tubes for interference should therefore be an integral part of the development and validation of any LC-MS/MS assay used in a clinical diagnostic laboratory., (Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objective: To complete a systematic review of emergency department (ED) practices for reducing hemolysis in blood samples sent to the clinical laboratory for testing., Results: A total of 16 studies met the review inclusion criteria (12 published and 4 unpublished). All 11 studies comparing new straight needle venipuncture with IV starts found a reduction in hemolysis rates, [average risk ratio of 0.16 (95% CI=0.11-0.24)]. Four studies on the effect of venipuncture location showed reduced hemolysis rates for the antecubital site [average risk ratio of 0.45 (95% CI=0.35-0.57]., Conclusions: Use of new straight needle venipuncture instead of IV starts is effective at reducing hemolysis rates in EDs, and is recommended as an evidence-based best practice. The overall strength of evidence rating is high and the effect size is substantial. Unpublished studies made an important contribution to the body of evidence. When IV starts must be used, observed rates of hemolysis may be substantially reduced by placing the IV at the antecubital site., (© 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: In an attempt to reduce false positive results and improve turnaround time, we investigated the BD Rapid Serum Tube as an alternate sample type to lithium heparin plasma for Roche Troponin T analysis on the Roche Cobas e411 analyzer., Design and Methods: BD Plasma Separator Tubes (PST) and Rapid Serum Tubes (RST) were collected in tandem from Emergency Department patients who had clinical orders for Troponin T over a 1 month period., Results: RST and PST samples yielded analytically and clinically concordant Troponin T results on the Roche Cobas e411. Rare false positive results in lithium heparin samples were not observed with rapid clot serum tubes., Conclusions: RST samples are appropriate for stat Troponin T analysis, and appear to reduce the incidence of rare false positive Troponin T results obtained with lithium heparin samples., (Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: Pre-analytical error decisively influences the total error and consequently the diagnostic accuracy. The following were the objectives for the study: 1. To detect the percent of pre-analytical errors in clinical biochemistry laboratory. 2. To categorize these pre-analytical errors. 3. To formulate corrective measures to be taken to avoid such errors., Design and Methods: Study period was for 3 months with documenting the frequency and type of pre-analytical errors occurring in the venous samples., Result: Average pre-analytical errors were 44.7% per day. Improper request, incorrect timing of sample, wrong tube collection and in-vitro hemolysis of samples amounted to the major proportion of errors., Conclusion: Pre-analytical errors occurring in each laboratory have to be checked. Such errors are not inevitable and can be avoided with a diligent application of quality control, continuing education and effective collection systems to ensure total quality patient care., (Copyright © 2011 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: To analyze the effect of blood collection and storage conditions on activity of α-galactosidase A, arylsulfatase B and α-glucosidase., Design and Methods: Blood was collected in EDTA, heparin, or direct spotting on filter paper and stored at different temperatures (-20, 4, 25 and 37°C) and storage times (3, 10, 17 and 180 days). The influence of filter paper size was also assessed (3.0 and 1.2mm)., Results: No statistically significant difference was observed between the three collection methods. α-Glucosidase A activity significantly decreased after the 10th day, while arylsulfatase B activity only differed significantly after the 180th day, and α-galactosidase A activity remained constant throughout this storage time. Excellent correlation coefficients were observed for the two filter paper sizes used., Conclusions: Both paper sizes may be employed. Filter paper specimens should be transported under refrigeration as soon as possible after blood collection., (Copyright © 2011 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Assays using dried blood samples have been in use for a number of years particularly for the diagnosis of inborn errors of metabolism. This sampling technique has been greatly helped by the sensitivity and specificity offered by liquid chromatography tandem mass spectrometry because of the limited amount of sample available for analysis. There are advantages for patients to take samples at home but these must be weighed against potential problems with the sampling technique. Some assays appear to work very well whilst others suffer from poor recovery because of adsorption of the analyte onto the filter paper. Some newer strategies including impregnation of the filter paper and filter filtration will be discussed. Calibration of assays and the problems with matrix matching of standards are also important issues that need to be addressed before an assay can be used routinely., (Copyright © 2010 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Background: We illustrate the impact of sample evaporation on analytical results in laboratory practice and highlight preventive measures., Methods: Plasma (n=10) was analysed for glucose, Na(+), HCO(3)(-) and calcium on six different sample configurations at 5 time points within 2h., Results: With time glucose, Na(+) and calcium values increased and HCO(3)(-) values decreased in a clinically significant way., Conclusions: Analytical error due to evaporation may be significant, but can be reduced with optimal sample handling. A pierceable cover does not prevent loss of HCO(3)(-)., (Copyright © 2010 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Objectives: To evaluate the effect of hemolysis on the measurement of insulin using the Beckman Coulter Unicell DXI 800 immunoassay analyzer., Design and Methods: Insulin concentrations were measured using the Beckman Coulter Unicell DXI 800. Interference studies were conducted by mixing plasma of known insulin concentrations with hemolysates of increasing hemoglobin concentration. Hemolysates were prepared by osmotic shock. A change of >10% from baseline results was taken as evidence of significant interference., Results: Hemolysates mediated a concentration-dependent reduction in insulin concentration., Conclusions: A concentration-dependent negative bias in the measurement of insulin is associated with increasing degrees of hemolysis on the Beckman Coulter Unicell DXI 800., (Copyright 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Blood collection devices interact with blood to alter blood composition, serum, or plasma fractions and in some cases adversely affect laboratory tests. Vascular access devices may release coating substances and exert shear forces that lyse cells. Blood-dissolving tube additives can affect blood constituent stability and analytical systems. Blood tube stoppers, stopper lubricants, tube walls, surfactants, clot activators, and separator gels may add materials, adsorb blood components, or interact with protein and cellular components. Thus, collection devices can be a major source of preanalytical error in laboratory testing. Device manufacturers, laboratory test vendors, and clinical laboratory personnel must understand these interactions as potential sources of error during preanalytical laboratory testing. Although the effects of endogenous blood substances have received attention, the effects of exogenous substances on assay results have not been well described. This review will identify sources of exogenous substances in blood specimens and propose methods to minimize their impact on clinical chemistry assays., (Copyright 2009 The Canadian Society of Clinical Chemists. All rights reserved.)

Objectives: To study an episode of excessive sample hemolysis associated with a recently installed pneumatic tube system from the Accident and Emergency Department., Design and Methods: Hemolysis rates in samples delivered with a tube system installed 3-4 months previously were followed up retrospectively and prospectively. The laboratory database was searched over a 3-year period for serum potassium results and the number of hemolyzed samples rejected that had been delivered by pneumatic tube or by hand., Results: Before the tube system was installed, the weekly mean hemolysis rate was 3.3%. After installation, the rate was 10.9% for 12 weeks but then it increased to 54%. After a fault was corrected, values fell to 9.0% and to 7.1% after samples were bubble-wrapped. Other wards served as controls., Conclusion: Laboratories should be aware that defects may arise in tube systems that may result in rapid sample deceleration and excessive hemolysis.

Objectives: To introduce a procedure to validate an ascorbic acid method using trichloroacetic acid (TCA) for plasma stabilization at different storage temperatures., Methods: EDTA and heparin plasma were precipitated with TCA (1:5) containing 0.54 mol/L EDTA, or without. Samples were stored at -20 degrees C and -70 degrees C and their stability was tested at room temperature for 24 h., Results: A significant 40% loss (p<0.001) of plasma ascorbic acid was found when EDTA samples with added EDTA were stored at -20 degrees C for 2-4 weeks compared with storage at -70 degrees C. Ascorbic acid in heparin plasma without added EDTA was most unstable and samples left at room temperature for 24 h lead to almost a total loss of ascorbic acid. Addition of EDTA to the TCA solution improved stability of samples of both plasma types at room temperature., Conclusion: The recommended procedure for ascorbic acid determination in plasma stabilized with TCA is immediate storage at -70 degrees C and inclusion of EDTA into the TCA solution.

Objectives: To identify the best procedure for preanalytical blood collection in the determination of matrix metalloproteinase (MMP)-2 and -9 by testing the effects of anticoagulants on their activity., Design and Methods: Active forms of both gelatinases were measured by specific activity assay systems in serum, plasma EDTA, plasma-heparin and plasma-citrate obtained from 20 healthy volunteers, as well as in a pooled serum sample before and after anticoagulant treatment., Results: : Active MMP-2 and MMP-9 mean concentrations were similar in serum and in plasma-citrate, higher in plasma EDTA than in serum, in plasma-heparin and in plasma-citrate, and lower in plasma-heparin than in serum and plasma-citrate. A similar trend was observed in untreated and treated pooled serum samples., Conclusions: Our results indicate that MMP-2 and MMP-9 in their active forms are not released by platelets during blood clotting, whereas the use of calcium chelating anticoagulants can profoundly alter the activity of endogenous gelatinases. This suggests that the determination of active forms of MMP-2 and MMP-9 in serum samples represents a suitable procedure.

Objectives: In large-scale genetic screening, an assay that is reliable, fast and easy to perform, and straightforwardly adapted to new analytes is a necessity. We describe a one-step assay for analyzing HLA-DQB1 alleles which are associated with susceptibility to type 1 diabetes., Design and Methods: The assay is based on asymmetric PCR amplification and a homogeneous hybridization method. The specificity of the probes was improved by substituting LNA (locked nucleic acid) for DNA at the critical bases., Results: The functionality of the LNA containing probes was found to be superior compared to probes consisting of DNA only. The homogeneous assay gave a correct genotyping result in 100% of the cases, which included both extracted DNA samples and blood samples dried on sample collection cards., Conclusion: This homogeneous approach provides a simple method to define disease risk associated with HLA alleles for large-scale screening projects.

Objectives: To evaluate the stability of insulin in serum and plasma under conditions relevant for the transport of samples from outpatient clinics to a centralized laboratory., Design and Methods: Venous blood samples were taken from 15 volunteers and processed either immediately or after storage at room temperature for 24 h. The effect of EDTA or sodium fluoride on insulin results was investigated., Results: Insulin was found to be stable in EDTA-containing tubes at room temperature for at least 24 h, whereas significantly lower concentrations were found if samples without additives or potassium fluoride as an additive were used., Conclusions: If shipment of patients' samples for insulin measurement from an outpatient clinic to a centralized laboratory can be performed within 24 h, centrifugation and freezing of plasma is not required. These findings facilitate a widespread application of insulin measurements to characterize and follow-up individual insulin sensitivity.

Objectives: The aim of the present study was to establish the range of chitotriosidase (CT) activity in normal individuals, patients with Gaucher disease (GD) and Niemann-Pick disease (NPD), types A or B. The kinetics of CT in these three groups was also investigated., Design and Methods: CT activity, as well as Km, Vmax, optimum pH, and thermal stability of the enzyme were determined in the plasma of control, GD, and NPD subjects., Results: CT activity in GD and NPD patients was, respectively, around 600-fold and 30-fold greater than in normal individuals. We observed significant differences in optimum pH, Vmax, and thermal stability between the various groups. Km was different in normal individuals relative to GD and NPD patients. However, there was no significant difference between Km values in patients with GD and with NPD., Conclusions: Based on the differences found in the biochemical parameters studied, our results may be important to help the identification of patients not only with GD but also with NPD.

Objectives: Heparin is thought to play a crucial role in the clinical monitoring of patients with acute coronary syndrome as well as after coronary bypass surgery in that it interferes with different commercial immunoassay test systems for cardiac troponin T (cTnT) and troponin I (cTnI). The mechanism, however, by which heparin apparently affects the cTnT and cTnI levels in plasma is not yet resolved., Design and Methods: We analyzed the effect of heparin by simultaneously collecting serum and heparin plasma samples from 32 patients after coronary bypass surgery. The cTnT and cTnI levels were determined using the Roche/Elecsys, the Dade-Behring/Opus and the Bayer/ACS:Centaur immunoassay systems in the absence or in the presence of either heparinase or protamine. Association between the cardiac troponins and the anticoagulant has been demonstrated by affinity chromatography using heparin as the ligand., Results: The data obtained indicate that heparin produces an apparent decrease in cTnT as well as of cTnI levels, analyzed either by the Elecsys, the Opus or the ACS:Centaur immunoassay systems. Individual patients show a wide variation in the discrepancies between serum and heparin plasma troponin especially in the cTnT immunoassay. Pretreatment of the heparin plasma samples either with heparinase or protamine cannot completely reverse the heparin-induced decrease in cTnT and cTnI levels and therefore addition of these reagents to the commercial test systems could not significantly improve the performance of the assay. When serum is supplemented with increasing concentrations of heparin, and cardiac troponin levels were reanalysed, significantly lower recoveries for the cTnT than for the cTnI immunoassays were detectable. Affinity chromatography with heparin Sepharose demonstrates that cTnT and cTnI interact differentially with the negatively charged ligand. Whereas cTnI shows minor affinity to the immobilized heparin and is eluted at near physiological conditions, cTnT is bound and can be quantitatively recovered only by solutions of high ionic strength., Conclusions: We conclude, therefore, that the apparent decrease in cTnT values by addition of heparin is a result of direct molecular interaction between the negatively charged glycosaminoglycan and clusters of basic residues within the sequence of the cardiac protein. In contrast, the effect of heparin on the cTnI immunoassay systems, is primarily indirect, most possibly induced by changes within the sample matrix itself., (Copyright 2002 The Canadian Society of Clinical Chemists)

Objective: To determine whether the well-established filter paper spotted blood method used for the determination of some amino acids could be reliably used to measure all amino acids and whether amino acid results thus obtained are reproducible and comparable to the results obtained by measuring plasma amino acids in either capillary or venous blood., Methods: This is a prospective study in which blood samples from a finger-prick were collected in capillary tubes and at the same time blotted on filter papers; another sample was taken from a vein, from 19 healthy volunteers aged between 18 and 24 yr after a strict 12-h overnight fast. Another 9 healthy adult volunteers provided blood samples on filter papers for the storage study; 9 samples were analyzed immediately; 9, 8 and 4 samples were stored at -20 degrees C, -4 degrees C and room temperature respectively and analyzed after 14 days; 8 samples stored at -20 degrees C were analyzed after 4 weeks., Results: Intra-sample reproducibility in the filter paper blood from the same individual was found to be mostly less than 20%, while for the capillary blood was less than 5%. The greatest variability was in cystine and methionine. There was no significant difference between results obtained from capillary blood and from venous blood, but there was a significant difference between amino acid concentrations in venous and capillary blood on the one hand and filter paper blood on the other. Storage at different temperatures and for a varied period of time showed little change except in serine, glutamate, ornithine, histidine, cystine and methionine. There was a 30% decrease in concentrations of most amino acids in filter paper blood when compared to capillary or venous blood probably because of loss in the extraction process., Conclusion: A new set of values for amino acids in filter paper blood in normal individuals is presented. Blood spotted filter paper could be used to screen practically all inborn errors of amino acid metabolism.

Point-of-care testing (POCT) has evolved from the demand for analytical information more rapidly than is available from central laboratories. By bringing the analysis closer to the patient several process steps have been eliminated, facilitating a shorter time to result and faster management response with improved outcomes. Thus benefits include better therapeutic turnaround times, decreased blood loss as a result of reduced phlebotomy secondary to clinical improvement, and diminished resource utilization. These advantages depend on acceptable analytical performance in comparison with central laboratory methods and in relation to clinical criteria. Generally these requirements are met but there are problems particularly with atypical specimens. Outcomes and cost-benefit analyses have been difficult to perform and evaluate. Given the multitude of participants, quality assurance and program management are recognized as resource intensive. However, recognition of problem areas is driving continuous improvement and we envisage expansion of this paradigm.

Objective: To assess the stability of PO2, PCO2 and pH in fresh individual blood samples drawn in a plastic syringe with low heparin and stored at 22 degrees C or on ice in relation to various biochemical and hematological parameters of the samples., Methods: PO2, PCO2, and pH were measured at determined times in samples kept at 22 degrees C or on ice. The magnitude of change in blood-gas parameters over time for each group of samples was determined. The change in PO2 was examined according to its initial value, the oxygen content (CaO2), the hemoglobin concentration, the leukocyte and platelet counts of each sample., Results: The changes in PO2, PCO2, and pH over time were about three times lower in samples stored on ice than in the ones at 22 degrees C. Nevertheless, rapid increases in PO2 were observed for samples stored on ice with an initial PO2 between 50 and 250 mm Hg. Samples with PO2 over 250 mmHg exhibited a decrease in PO2 over time. No correlation was observed between the change in PO2 and the oxygen content, the hemoglobin concentration or the leukocyte and platelet counts for both groups of samples stored at 22 degrees C or on ice., Conclusion: PO2 in samples with an initial PO2 between 50 and 250 mm Hg stored on ice should be analyzed within 30 min. However, PCO2 and pH didn't exhibit clinically significant changes within 60 min under similar conditions. The magnitude of change in PO2 for samples kept on ice was dependent on their hemoglobin capacity for buffering oxygen, which is in converse relation with the oxygen saturation level of hemoglobin (SatHbO2). It is believed that the alteration in PO2 for samples stored on ice is produced predominantly by diffusion of oxygen through the plastic wall of the syringe, whereas it would be mainly of metabolic origin in samples at room temperature.

Objective: To evaluate the suitability of the thrombin inhibitors PPACK (D-phenylalanyl-L-prolyl-L-arginine chloromethylketone) or Argatroban for anticoagulation of blood prior to critical care testing of whole blood or plasma., Design and Methods: Initially we evaluated the effect of PPACK (0-200 microM) or Argatroban (0-590 microM) on serum glucose, urea, creatinine, calcium and electrolyte tests on two chemistry analyzers (Hitachi 717 and Ektachem 700XR). Subsequently plasma and serum from whole blood samples containing either heparin 15,000 IU/L or PPACK 75 microM or Argatroban 245 microM or no anticoagulant were tested and compared. We analysed and compared whole blood containing either PPACK 75 microM or Argatroban 245 microM or ethylenediaminetetraacetic acid (EDTA) using a Coulter STK-R hematology analyzer at intervals for 90 minutes., Results: The measurement of electrolytes, urea, creatinine, calcium or glucose was unaffected by either Argatroban or PPACK in either serum or anticoagulant-specific plasmas (p > 0.05). For specimens from individual donors, serum potassium was higher than plasma potassium, irrespective of anticoagulant used. Clinically equivalent complete blood counts were achieved for 60 minutes using EDTA-whole blood, or whole blood containing 245 microM Argatroban or 75 microM PPACK. However automated differential white cell counting was not reliable with either form of thrombin inhibitor-whole blood. Argatroban-anticoagulated blood demonstrated concentration and time dependent changes in platelet counts, whereas platelet counts were stable in blood containing 75 microM PPACK for up to 90 minutes., Conclusion: Specimens of blood anticoagulated with either 75 microM PPACK or 245 microM Argatroban can be used for either critical care chemistry or hematology testing.

The monitoring of cyclosporine (CsA) whole blood concentrations is an integral part of immunosuppressive treatment with this drug. Although such monitoring has been facilitated by the introduction of monoclonal immunoassay techniques, there is a paucity of published data comparing the assays longitudinally in selected patients. The purpose of our study was to co-evaluate two monoclonal immunoassays (Cyclosporine FPIA whole blood assay, Abbott Laboratories; Cyclo-Trac SP-whole blood RIA, Incstar Inc.) and a high-performance liquid chromatography (HPLC) technique for quantitating CsA in sequentially collected trough whole blood samples from 14 patients up to 75 days after renal (n = 6), heart (n = 3), and liver (n = 5) transplantation. HPLC CsA metabolite analyses (AM1, AM9, AM4N) were performed. Although CsA concentrations within most patients were significantly higher (p < 0.05, paired t test) when measured by both immunoassay techniques compared to HPLC, levels determined in three patients, (one liver, two renal) for the FPIA/HPLC comparison and one patient (liver) for the RIA/HPLC comparison were not significantly different (p > 0.05). CsA levels within nine patients were not significantly different (p > 0.05) when FPIA and RIA were compared, but results within three patients, (one liver, two renal) were significantly higher (p < 0.05) by RIA compared to FPIA, but results within one patient (heart) were significantly higher (p < 0.05) by FPIA. Our results demonstrate first that depending on the patient, HPLC-derived CsA results are not consistently lower than results generated by immunoassay techniques and second that CsA levels obtained by FPIA are statistically equivalent or in some patients, statistically less than RIA-derived levels.

Two studies are described in this paper for the purpose of extending the application of the Dupont ACA glucose method to (1) analysis of specimens containing sodium fluoride and sodium iodoacetate, and (2) analysis of specimens containing EDTA, provided analysis is conducted immediately following specimen collection and sample processing.