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Background The remote performance of thyroid function blood tests is complicated because it requires blood collection. Objective To compare TSH and free thyroxine (FT4) levels between capillary and venous blood and assess the adequacy of measuring each value in capillary blood. Methods This prospective intervention study was conducted at Ito Hospital and was based on the clinical research method. The participants were 5 healthy female volunteers and 50 patients (41 females and 9 males) between the ages of 23 and 81 years. To measure TSH and FT4 levels in capillary and venous blood, a digital immunoassay (d-IA) method capable of measuring trace samples was used. Chemiluminescence measurements were used as controls. Values obtained for each assay system were compared using Spearman's correlation analysis. Capillary blood was collected using an autologous device (TAP II; not approved in Japan). Results Capillary plasma volume obtained using TAP II was 125 µL or more in 26 cases, 25 µL to 124 µL in 24 cases, and less than 25 µL in 5 cases. Strong correlations were noted in the TSH and FT4 levels between capillary and venous blood, with correlation coefficients of rs = 0.99 and rs = 0.97, respectively. Conclusion Capillary TSH and FT4 levels strongly correlate with venous blood values. Trace samples can be used in high-precision d-IA methods. These results may promote telemedicine in assessing thyroid function. [ABSTRACT FROM AUTHOR]

Remote self-collected capillary blood samples have been proposed as alternative to venous blood samples as an aid in telemedicine. The aim of this work is to compare the preanalytical and analytical performance of these two types of samples and to study the stability of common measurands in capillary blood. Capillary and venous blood samples were collected in parallel from 296 patients in serum tubes to analyze 22 common biochemistry magnitudes after centrifugation and in EDTA tubes to analyze 15 hematologic magnitudes. Quality of the preanalytical process was assessed applying the model of quality indicator. 24 h stability at room temperature was studied by obtaining paired capillary samples. A questionnaire of assessment was conducted. Mean hemolysis index was higher in capillary samples compared to venous blood samples (p<0.001). Regression analysis and difference analysis showed no bias for all studied biochemistry parameters and hematologic parameters, except mean corpuscular volume (MCV), between capillary and venous blood samples. Regarding sample stability, percentage deviation was higher than the corresponding minimum analytical performance specification for ferritin, vitamin D, hematocrit, MCV, mean corpuscular hemoglobin concentration, platelets distribution wide, mean platelet volume and basophils. Finger pricking was perceived as less painful (p<0.05) than venipuncture in participants who undergo more than one blood test per year. Capillary blood can be used as an alternative to venous blood for the studied parameters in automated common clinical analyzers. Cautious should be taken if samples are not analyzed within 24 h from the collection. [ABSTRACT FROM AUTHOR]

It is well known that acute hypoxia has negative effects on balance performance. An attempt to compensate for the influence of hypoxia on competition performance was made by the application of hyperoxic gases (inspiratory fraction of oxygen > 0.2095) prior to exercise. Purpose: To investigate whether hyperoxic preconditioning (pure-oxygen supplementation prior to exercise) improves balance ability and postural stability during normobaric hypoxia (3500 m) in highly skilled skiers. Methods: In this single-blind randomized, crossover study, 19 subjects perlormed a 60-s balance test (MFT S3-Check) in a normobaric hypoxic chamber. After a short period of adaptation to hypoxia (60 min), they received either pure oxygen or chamber air for 5 min prior to a balance test (hyperoxic preconditioning vs nonhyperoxic preconditioning). Capillary blood was collected 3 times. Results: Balance performance, indexed by sensory (P = .097), stability (P = .937), and symmetry (P = .202) scores, was not significantly different after the hyperoxic preconditioning phase. Balance performance decreased over time (no group difference). After hyperoxic preconditioning, arterial partial pressure of oxygen increased from 52.7 (4.5) mm Hg to 212.5 (75.8) mm Hg, and oxygen saturation of hemoglobin increased from 85.8% (3.5%) to 98.9% (0.7%) and remained significantly elevated to 90.1% (2.0%) after the balance test. Conclusion: A hyperoxic preconditioning phase does not affect balance performance under hypoxic environmental conditions. A performance-enhancing effect, at least in terms of coordinative functions, was not supported by this study. [ABSTRACT FROM AUTHOR]

Population-based surveys commonly use point-of-care (POC) methods with capillary blood samples for estimating Hb concentrations; these estimates need to be validated by comparison with reference methods using venous blood. In a cross-sectional study in 748 participants (17–86 years, 708 women, Hb: 5·1 to 18·2 g/dl) from Hyderabad, India, we validated Hb measured from a pooled capillary blood sample by a POC autoanalyser (Horiba ABX Micros 60OT, Hb-C-AA) by comparison with venous blood Hb measured by two reference methods: POC autoanalyser (Hb-V-AA) and cyanmethemoglobin method (Hb-V-CM). These comparisons also allowed estimation of blood sample-related and equipment-related differences in the Hb estimates. We also conducted a longitudinal study in 426 participants (17–21 years) to measure differences in the Hb response to iron folate (IFA) treatment by the capillary blood POC method compared with the reference methods. In the cross-sectional study, Bland–Altman analyses showed trivial differences between source of blood (Hb-C-AA and Hb-V-AA; mean difference, limits of agreement: 0·1, −0·8 to 1·0 g/dl) and between analytical methods (Hb-V-AA and Hb-V-CM; mean difference, limits of agreement: < 0·1, −1·8 to 1·8 g/dl). Cross-sectional anaemia prevalence estimated using Hb-C-AA did not differ significantly from Hb-V-CM or Hb-V-AA. In the longitudinal study, the Hb increment in response to IFA intervention was not different when using Hb-C-AA (1·6 ± 1·7 g/dl) compared with Hb-V-AA (1·7 ± 1·7 g/dl) and Hb-V-CM (1·7 ± 1·7 g/dl). The pooled capillary blood–autoanalyzer method (Hb-C-AA) offers a practical and accurate way forward for POC screening of anaemia. [ABSTRACT FROM AUTHOR]

Purpose: Dried blot spot (DBS) analysis of drugs or clinical parameters offers many advantages. We investigated the feasibility of using DBS for analysis of anti-diabetic drugs concomitantly with the estimated creatinine clearance (Clcrea). Methods: The cross-sectional study involved physicians in an enabling analysis with 70 diabetic patients and community pharmacists in a field investigation with 84 participants. All 154 DBS samples were analyzed for creatinine, metformin, and sitagliptin. Results: The diabetic patients revealed of a wide range of age (32–88 years), BMI values (19.8–54.7 kg/m2), and extent of polypharmacotherapy (1–21 drugs). A correlation factor to convert capillary blood creatinine from DBS into plasma concentrations was determined. Patients' Clcrea ranged from 21.6–155.9 mL/min. The results indicated statistically significant correlations (p < 0.05) between the use of two or three particular drug classes (diuretics, NSAIDs, renin-angiotensin system blockers) and a decreased renal function. DBS concentrations of metformin ranged between 0.23–4.99 μg/mL. The estimated elimination half-life (t ½) of metformin was 11.9 h in patients with a ClCrea higher than 60 mL/min and 18.5 h for diabetics with lower ClCrea. Sitagliptin capillary blood concentrations ranged between 11.12–995.6 ng/mL. Calculated t ½ of sitagliptin were 8.4 h and 13.0 h in patients with a ClCrea above and below 60 mL/min, respectively. Conclusions: DBS allow for the analysis of concentrations of predominantly renally eliminated drugs and community pharmacists can provide a valuable contribution to DBS sampling. [ABSTRACT FROM AUTHOR]

Clinically, blood sample analysis has been widely used for health monitoring. In hospitals, arterial and venous blood are utilized to detect various disease biomarkers. However, collection methods are invasive, painful, may result in injury and contamination, and skilled workers are required, making these methods unsuitable for use in a resource-limited setting. In contrast, capillary blood is easily collected by a minimally invasive procedure and has excellent potential for use in point-of-care (POC) health monitoring. In this review, we first discuss the differences among arterial blood, venous blood, and capillary blood in terms of the puncture sites, components, sample volume, collection methods, and application areas. Additionally, we review the most recent advances in capillary blood-based commercial products and microfluidic instruments for various applications. We also compare the accuracy of microfluidic-based testing with that of laboratory-based testing for capillary blood-based disease diagnosis at the POC. Finally, we discuss the challenges and future perspectives for developing capillary blood-based POC instruments. [ABSTRACT FROM PUBLISHER]

Background In field studies, hemoglobin (Hb) is often measured using a battery-operated, portable HemoCue® hemoglobinometer. Methods We compared the performance of 2 HemoCue® models (Hb-201+ and Hb-301) and investigated effects of preanalytical factors on Hb results by simulating unfavorable field conditions. Results The Hb-301 produced 2.6% higher results compared to the Hb-201+. Hb had to be measured within 1 min of filling the Hb-301 cuvette to avoid artificially elevated concentrations (1.3% per min). The Hb-301 cuvettes withstood elevated temperature (37 °C) and humidity (72%) for 3 weeks, while the Hb-201+ cuvettes degraded within 10 min under those conditions. Both cuvette types withstood elevated temperature for 3 weeks. Properly-collected venous and capillary blood produced comparable results. Pooled capillary blood produced comparable results to the second and third but not the fourth drop of blood (3.3% lower). Blood could be stored for ≤ 4 days at 10–30 °C before Hb-201+ measurement, but only for 1 day at 10–23 °C before Hb-301 measurement (≤ 1% change in Hb). Conclusions Higher Hb results obtained with the Hb-301 may influence the interpretation of anemia prevalence in health surveys. While the Hb-301 performed better in high humidity conditions, the Hb-201+ provided more user flexibility regarding delayed Hb reading. [ABSTRACT FROM AUTHOR]

Objectives: Blood obtained via fingerprick is commonly used in point-of-care assays, but few studies have assessed variability in parameters obtained from successive drops of fingerprick blood, which may cause problems for clinical decision making and for assessing accuracy of point-of-care tests.Methods: We used a hematology analyzer to analyze the hemoglobin concentration, total WBC count, three-part WBC differential, and platelet count in six successive drops of blood collected from one fingerprick from each of 11 donors, and we used a hemoglobinometer to measure the hemoglobin concentration of 10 drops of fingerprick blood from each of 7 donors.Results: The average percent coefficient of variation (CV) for successive drops of fingerprick blood was higher by up to 3.4 times for hemoglobin, 5.7 times for WBC count, 3 times for lymphocyte count, 7.7 times for granulocyte count, and 4 times for platelets than in venous controls measured using a hematology analyzer. The average percent CV for fingerprick blood was up to 5 times higher for hemoglobin than venous blood measured using a point-of-care hemoglobinometer. Fluctuations in blood parameters with increasing volume of fingerprick blood are within instrument variability for volumes equal to or greater than 60 to 100 μL.Conclusions: These data suggest caution when using measurements from a single drop of fingerprick blood. [ABSTRACT FROM AUTHOR]

Abstract: Background: Glucose oxidase biosensors are used in self-monitoring blood glucose concentrations. The capillary blood glucose quantitation requires a calibration curve. Due to the limitation in obtaining calibration curve from capillary blood, an alternate approach by using venous blood for neonatal measurement was investigated. Methods: A signal correlation between oxygen saturated venous blood and capillary blood was derived. The hematocrit effect was studied for different glucose concentrations. The calibrated glucose strips were validated by neonatal intensive care unit (NICU) samples. Results: A simple equation, finger blood signal=1.39∗(oxygen saturated venous blood signal)−31.2 was derived. The rate of change in glucose concentration due to hematocrit effect was low in lower glucose concentration samples. The BeneCheck Glucose Strips were compared with Beckman Coulter analyzer by using 52 NICU samples. More than 95% of test results were within the variation of ±10mg/dl of bias and ±15% of bias% when glucose concentration is <75mg/dl and ≥75mg/dl respectively. Conclusions: The BeneCheck Glucose Strips can be accurately calibrated with venous blood. The hematocrit effect can also be predicted. Based on this study, BeneCheck Blood Glucose Monitoring System can be suitable for neonatal glucose measurement. [Copyright &y& Elsevier]

Abstract: Background: Point-of-care devices for performing a prothrombin time/international normalized ratio (PT/INR) using capillary blood samples are being increasingly used to monitor patients receiving anticoagulation therapy. However, the performance of some devices has been shown to be suboptimal and there are only limited published data comparing specific devices to various central laboratory coagulation analyzers. We report an evaluation of the iSTAT PT/INR with a comparison to the Tcoag MDA II analyzer. Methods: We obtained simultaneous capillary/venous samples on 20 healthy volunteers for a normal range study and on 50 anticoagulated patients for a clinical evaluation. Testing was performed by phlebotomists. We also obtained 68 near simultaneous capillary/venous test results for assessment of performance by non-laboratory personnel. The criteria for determining clinical equivalence of the iSTAT to the MDA II were (1) same clinical category (subtherapeutic INR<2, therapeutic INR 2–3, and supratherapeutic INR>3) or (2) paired values within ≤0.4 INR. Results: Forty nine of 50 patient sample pairs collected by phlebotomists showed acceptable clinical agreement. Sixty one (61) of 68 patient sample pairs collected by nurses showed acceptable agreement. In all discordant cases the differences were minor and would have resulted in either no or minimal change in therapy. Conclusions: The iSTAT PT/INR compares well to the MDA II when performed by phlebotomists or nurses. [Copyright &y& Elsevier]

Abstract: Background: An electrochemical based biosensor for hemoglobin measurement was developed as an alternative to the traditional optical method, and underwent testing for use in professional settings. Methods: The affects of samples'' freshness, hemolysis, bilirubin on the electrochemical method, as well as the repeatability, precision and accuracy were studied, using optical method devices as references. Results: Samples were stored at room temperature or in a cold environment for 7days, partially or completely hemolyzed samples, and samples containing bilirubin with a concentration of up to 150mg/l were investigated with no effects for interfering studies. Repeatability of finger blood testings was verified with six consecutive tests on nine volunteers, results ranged from 3% to 8% variation. The test results of BeneCheck were correlated with Sysmex, Beckman Coulters, Cell-Dyn and HemoCue methods, the results have shown similar and 95% of test results were within a ±15% bias. Conclusions: BeneCheck hemoglobin test system performed well and accurately, while requiring 1μl of blood sample and 10s detection time. Based on the cost, accuracy, sample volume, measuring time, ease of viewing and portability, BeneCheck deliver the best characteristics for these purposes. [Copyright &y& Elsevier]

Background: This study evaluates HbA1c measurements from dried blood spots collected on filter paper and compares HbA1c from filter paper (capillary blood) with HbA1c measured in venous blood. Methods: Patient satisfaction was evaluated using a questionnaire. The performance with the filter paper method was assessed by comparing HbA1c results from EDTA-blood samples obtained via dried blood spots with HbA1c results obtained with freshly hemolyzed blood (routine HbA1c). Adult patients visiting the outpatient clinic for HbA1c analyses were recruited for the evaluation of dried blood spot sampling at home. Laboratory personnel collected a capillary blood sample on filter paper as well as a venous EDTA-blood sample. The participants collected another capillary blood sample at home and sent the dried filter paper back to the laboratory. Samples were analyzed with an immunoturbidimetric assay. Results: Between-filter coefficient of variation was 1.8%. Filter paper HbA1c increased slightly during storage, particularly during the first 5 days. Filter paper HbA1c highly correlated with routine HbA1c (r=0.987). The evaluation of samples collected at home showed comparable HbA1c values by filter paper and routine sampling methods (n=93). Eighty-three percent of participants said they would like the filter method to be brought into practice. Conclusions: Home HbA1c sampling on filter paper is an acceptable sampling alternative for analysis of HbA1c. Clin Chem Lab Med 2009;47:1259–64. [ABSTRACT FROM AUTHOR]

To compare the accuracy of fingerstick with laboratory venous plasma glucose measurements (laboratory glucose) in medical ICU patients and to determine the factors which interfere with the accuracy of fingerstick measurements. The study included 80 consecutive patients aged 58 ± 7 years, BMI 29.5 ± 9.0, and APACHE II score 15 ± 6 (277 simultaneous paired measurements). This prospective observational study compared fingerstick measurements to simultaneously sampled laboratory glucose once a day in patients in our medical ICU (twice daily if on an insulin infusion). Data recorded included patient demographics, admission diagnoses, APACHE II score, BMI, daily hematocrit, arterial blood gasses, chemistry results, concomitant medications (including vasopressors and corticosteroids), and upper extremity edema. Accuracy was defined as the percentage of paired values not in accord (> 15 mg dl–1 / 0.83 mmol–1 l–1 difference for laboratory values < 75 mg dl–1 / 4.12 mmol–1 l–1 and > 20% difference for laboratory values ≥ 75 mg/dl). Outliers (blood glucose difference > 100 mg dl–1 / 5.56 mmol–1 l–1) were excluded from the correlation and distribution analyses. Mean fingerstick glucose was 129 ± 45 mg/dl (7.2 ± 2.5 mmol/l) and mean laboratory glucose 123 ± 44 mg/dl (6.8 ± 2.4 mmol/l). The correlation coefficient between the two values was 0.9110 (Clinical and Laboratory Standards Institute threshold 0.9751). The mean difference (bias) between the two methods was 8.6 ± 18.6 mg/dl (0.48 ± 1.0 mmol/l) and limits of agreement +45.8 and –28.6 mg/dl (+2.5 and –1.6 mmol/l). Fifty-three (19%) paired measurements in 22 patients were not in accord (CLSI threshold ≤ 5%). In 44 (83%) of these paired measurements fingerstick glucose was greater than laboratory glucose. The findings suggest that capillary blood glucose as measured by fingerstick is inaccurate in critically ill ICU patients and does not meet the CLSI standard. It is unclear whether the sampling method, device used, or both contributed to this inaccuracy. The wide limits of agreement suggest that fingerstick measurements should be used with great caution in protocols of tight glycemic control. [ABSTRACT FROM AUTHOR]

Abstract: A bioanalytical method for the determination of lumefantrine in 100μl blood applied onto sampling paper, by solid-phase extraction and liquid chromatography, has been developed and validated. Whatman 31 ET Chr sampling paper was pre-treated with 0.75M tartaric acid before sampling capillary blood to enable a high recovery of lumefantrine. Lumefantrine was extracted from the sampling paper, then further purified using solid-phase extraction and finally quantified with HPLC. The between-day variation was below 10% over the range 0.4–25μM. The lower limit of quantification was 0.25μM in 100μl capillary blood. No decrease in lumefantrine concentration in dried blood spot is seen after 4 months storage at 22°C. The method was also evaluated in field samples from patients in Tanzania after treatment with lumefantrine/artemether. Lumefantrine could be estimated accurately enough to assess bioavailability and treatment compliance on day 7 (i.e. 4 days after the last dose) after a standard regimen with the lumefantrine/artemether combination. [Copyright &y& Elsevier]

Background: Oral anticoagulant therapy is monitored by a prothrombin time (PT) assay. The PT is standardised by the International Normalised Ratio (INR). The purpose of this study was to work out a modified method of PT/INR measurement in capillary blood for monitoring anticoagulation treatment. Methods: Healthy donors, subjects with high or low haematocrit values, and oral anticoagulant-treated patients were included in the study. Plasma and capillary blood PT/INRs were determined by the standard Quick clotting assay, by the modified approach and with the CoaguChek S analyser. Results: The performance characteristics of the developed method were accuracy, due to taking into account whole capillary blood haematocrit values, and precision, due to a decrease in the viscosity of the analysed samples. Implementation of the modified method showed that it is possible to use PT values of normal plasma for capillary blood INR calculation. The developed method allowed the determination of PT in capillary blood within the haematocrit value range from 0.15 up to 0.7. For capillary blood, the results of the modified method closely correlated with PT/INR values determined by the reference Quick method in venous plasma (r=0.99) and with the CoaguChek S analyser (r=0.97). Conclusions: The modified method of capillary blood PT/INR determination could be recommended for oral anticoagulant therapy monitoring. Clin Chem Lab Med 2006;44:1214–7. [ABSTRACT FROM AUTHOR]