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Objectives: Fecal immunochemical tests (FIT) for hemoglobin are currently considered the screening investigation of choice for colorectal cancer and are worldwide recommended. Similarly, fecal calprotectin is a widely used test for monitoring intestinal inflammation. The pre-analytical issues regarding stool samples have hardly been dealt with and are difficult to solve. Currently, there are no reference analytes available which allow to correct test results for the variable water content of the stool sample. Studies on preanalytics of stool samples have generally focused on sample preparation and sample storage, but generally have paid little attention to the variability in sample hydration and sample composition., Methods: Stercobilin is a stable heme metabolite which is abundant in stool. Stercobilin concentration can be simply assayed in stool extracts using colorimetry (determination of the I index). Serum indices (H, I and L) and bilirubin concentration of fecal extracts were determined on a Atellica Platform (Siemens)., Results: The inter-individual variation of stercobilin was found to be high. Assaying stercobilin allows to correct for stool sample dilution. The median value of the I-index was used as a reference for correcting the data. Correcting fecal blood results for sample dilution resulted in a significant increase in positive tests (from 9.3 to 11.7 %). For calprotectin, correction resulted in 3.1 % extra positive results and 7.7 % negative results., Conclusions: Except in the case of obstructive jaundice, this correction can be applied. Correcting test results of common fecal analytes like FIT and calprotectin may result in a better tailored test interpretation., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)

Objectives: Amphotericin B (AmB) is the gold standard for treating invasive fungal infections. New liposomal-containing AmB formulations have been developed to improve efficacy and tolerability. Serum/plasma C-reactive protein (CRP) values are widely used for monitoring infections and inflammation. CRP shows a high affinity to phosphocholine and it aggregates structures bearing this ligand, e.g. phosphocholine-containing liposomes. Therefore, we studied the interaction between CRP and phosphocholine-containing liposomal AmB preparations in vivo and in vitro ., Methods: CRP was prepared by affinity chromatography. Liposomal AmB (L-AmB, AmBisome ® ) was spiked (final concentrations of L-AmB: 150 mg/L) to CRP-containing serum (final CRP concentration: 300 mg/L). Following the addition of L-AmB, complex formation was monitored turbidimetrically. The size of CRP-L-AmB complexes was assessed using gel filtration. CRP was monitored in patients receiving either L-Amb or AmB lipid complex (ABLC)., Results: Following addition of L-AmB to CRP-containing plasma, turbidimetry showed an increase in absorbance. These results were confirmed by gel permeation chromatography. Similarly, in vivo effects were observed following intravenous administration of AmBisome ® : a decline in CRP values was observed. In patients receiving L-Amb, decline of CRP concentration was faster than in patients receiving ABLC., Conclusions: In vitro experiments are suggestive of a complexation between CRP and liposomes in plasma. Interpretation of CRP values following administration of AmBisome ® might be impaired due to this complexation. In vivo formation of complexes between liposomes and CRP might contribute, or even lead, to intravascular microembolisation. Similar effects have been described following the administration of Intralipid ® and other phosphocholine-containing liposomes., (© 2023 Walter de Gruyter GmbH, Berlin/Boston.)

Objectives: Diabetes mellitus is a major public health problem. Hemoglobin A 1c (HbA 1c ) is a key laboratory parameter in the management of diabetes patients. However, in diabetes monitoring, interpretation of HbA 1c results is hampered by the important interindividual variation in red blood cell (RBC) life span. Furthermore, HbA 1c only slowly responds to changes in glucose metabolism. Besides HbA 1c , there exists a labile HbA 1c fraction (l-HbA 1c ), exhibiting much faster kinetics. As both HbA 1c and l-HbA 1c are measured by modern standard chromatography, we explored the possibilities of using the l-HbA 1c fraction for monitoring glycemia., Methods: l-HbA 1c and HbA 1c fractions were simultaneously assayed on a Tosoh G8 analyzer and expressed as %. l-HbA 1c results were compared with serum glucose and HbA 1c . Concomitantly, RBC distribution width (RDW) was determined on a Sysmex SN analyzer as a marker for erythrocyte life span., Results: l-HbA 1c could be measured with between-run coefficient of variations (CVs) between 2.2 and 2.3%. l-HbA 1c correlated with both glycemia (r=0.80) and HbA 1c results (r=0.73). In a multiple regression model (r 2 =0.752), glycemia and HbA 1c were the most determining factors. To a lesser extent, RDW correlated with l-HbA 1c (r=0.158). Furthermore, the l-HbA 1c /HbA 1c ratio weakly positively correlated with RDW (r=0.247)., Conclusions: L-HBA 1c represents an additional marker for monitoring the rapid occurrence of glycemic disorders that escape detection when using only HbA 1c and blood glucose. RDW can be used as an indicator of atypical RBCs life span, in which the l-HbA 1c fraction may be helpful., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)

Objectives In this study, the possibilities of Fourier-transformed infrared spectroscopy (FTIR) for analysis of urine sediments and for detection of bacteria causing urinary tract infections (UTIs) were investigated. Methods Dried urine specimens of control subjects and patients presenting with various nephrological and urological conditions were analysed using mid-infrared spectroscopy (4,000-400 cm-1). Urine samples from patients with a UTI were inoculated on a blood agar plate. After drying of the pure bacterial colonies, FTIR was applied and compared with the results obtained by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Chemometric data analysis was used to classify the different species. Results Due to the typical molecular assignments of lipids, proteins, nucleic acids and carbohydrates, FTIR was able to identify bacteria and showed promising results in the detection of proteins, lipids, white and red blood cells, as well as in the identification of crystals. Principal component analysis (PCA) allowed to differentiate between Gram-negative and Gram-positive species and soft independent modelling of class analogy (SIMCA) revealed promising classification ratios between the different pathogens. Conclusions FTIR can be considered as a supplementary method for urine sediment examination and for detection of pathogenic bacteria in UTI.

Background Diagnosis of upper urinary tract infections (UTI) is challenging. We evaluated the analytical and diagnostic performance characteristics of renal tubular epithelial cells (RTECs) and transitional epithelial cells (TECs) on the Sysmex UF-5000 urine sediment analyzer. Methods Urinary samples from 506 patients presenting with symptoms of a UTI were collected. Only samples for which a urinary culture was available were included. Analytical (imprecision, accuracy, stability and correlation with manual microscopy) and diagnostic performance (sensitivity and specificity) were evaluated. Results The Sysmex UF-5000 demonstrated a good analytical performance. Depending on the storage time, storage conditions (2-8 °C or 20-25 °C) and urinary pH, RTECs and TECs were stable in urine for at least 4 h. Using Passing-Bablok and Bland-Altman analysis, an acceptable agreement was observed between the manual and automated methods. Compared to TECs, RTECs demonstrated an acceptable diagnostic performance for the diagnosis of upper UTI. Conclusions While TECs do not seem to serve as a helpful marker, increased urinary levels of RTECs add value in the diagnosis of upper UTI and may be helpful in the discrimination between upper and lower UTIs.

Background Urinary conductivity allows a coarse prediction of urinary osmolality in most cases but is insensitive to the osmolal contribution of uncharged particles and the presence of roentgen contrast media. Urinary osmolality can be estimated on the recently introduced Sysmex UF-5000 urine analyzer using conductivity. In this study, we evaluated the analytical performance of this research parameter. Secondly, we aimed to improve the manufacturer's algorithm for estimating urinary osmolality, based on standard urinalysis parameters (creatinine, glucose, relative density). Methods The analytical performance was determined and a prediction model to estimate urinary osmolality based on urinalysis parameters was developed. We further developed and validated a prediction model using another set of routine urine samples. In addition, the influence of roentgen contrast media on urinary osmolality was studied. Results The within-run and between imprecision for osmolality and conductivity measured on the Sysmex UF-5000 ranged from 1.1% to 4.9% and 0.7% to 4.8%, respectively. Multiple regression analysis revealed urinary creatinine, conductivity and relative density to be the strongest predictors to estimate urinary osmolality. A mean difference of 1.3 mOsm/kg between measured and predicted osmolality demonstrated that the predictive performance of our model was favorable. An excellent correlation between the relative density and % contrast media was demonstrated. Conclusions Urinary osmolality is an important parameter for assessing specimen dilution in urinalysis. Urinary conductivity, along with relative density and urinary creatinine allows a coarse prediction of urinary osmolality and is insensitive to the osmolal contribution of uncharged particles and the presence of roentgen contrast media.