Renal tubular epithelial cells add value in the diagnosis of upper urinary tract pathology

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 degrees C or 20-25 degrees 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

Interference of glucose and total protein on Jaffe-based creatinine methods : mind the covolume

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Estimated urinary osmolality based on combined urinalysis parameters : a critical evaluation

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

Quantitative urine test strip reading for leukocyte esterase and hemoglobin peroxidase

Background: Recently, urine test strip readers have become available for automated test strip analysis. We explored the possibilities of the Sysmex UC-3500 automated urine chemistry analyzer based on complementary metal oxide semiconductor (CMOS) sensor technology with regard to accuracy of leukocyte esterase and hemoglobin peroxidase results. We studied the influence of possible confounders on these measurements. Methods: Reflectance data of leukocyte esterase and hemoglobin peroxidase were measured using CMOS technology on the Sysmex UC-3500 automated urine chemistry analyzer. Analytical performance (imprecision, LOQ) as well as the correlation with white blood cell (WBC) and red blood cell (RBC) counts (Sysmex UF-5000) were studied. Furthermore, the influence of urinary dilution, haptoglobin, pH and ascorbic acid as confounders was determined. Results: Within- and between-run imprecision (reflectance signal) ranged from 1.1% to 3.6% and 0.9% to 4.2% for peroxidase and 0.4% to 2.5% and 0.4% to 3.3% for leukocyte esterase. Good agreement was obtained between the UF-5000 for RBCs and peroxidase reflectance (r = 0.843) and for WBCs and leukocyte esterase (r = 0.821). Specific esterase activity decreased for WBC counts exceeding 100 cells/mu L. Haptoglobin influenced the peroxidase activity, whereas leukocyte esterase and peroxidase activities showed a pH optimum between 5.0 and 6.5. A sigmoidal correlation was observed between urinary osmolality and peroxidase activity. Conclusions: CMOS technology allows to obtain high quality test strip results for assessing WBC and RBC in urine. Quantitative peroxidase and leukocyte esterase are complementary with flow cytometry and have an added value in urinalysis, which may form a basis for expert system development

Analytical and pre-analytical performance characteristics of a novel cartridge-type blood gas analyzer for point-of-care and laboratory testing

Background: Point-of-care blood gas test results may benefit therapeutic decision making by their immediate impact on patient care. We evaluated the (pre-) analytical performance of a novel cartridge-type blood gas analyzer, the GEM Premier 5000 (Werfen), for the determination of pH, partial carbon dioxide pressure (pCO(2)), partial oxygen pressure (pO(2)), sodium (Na+), potassium (K+), chloride (Cl-), ionized calcium (iCa(2+)), glucose, lactate, and total hemoglobin (tHb). Methods: Total imprecision was estimated according to the CLSI EP5-A2 protocol. The estimated total error was calculated based on the mean of the range claimed by the manufacturer. Based on the CLSI EP9-A2 evaluation protocol, a method comparison with the Siemens RapidPoint 500 and Abbott i-STAT CG8 + was performed. Obtained data were compared against preset quality specifications. Interference of potential pre-analytical confounders on co-oximetry and electrolyte concentrations were studied. Results: The analytical performance was acceptable for all parameters tested. Method comparison demonstrated good agreement to the RapidPoint 500 and i-STAT CG8 +, except for some parameters (RapidPoint 500: pCO(2), K+, lactate and tHb; i-STAT CG8 +: pO(2), Na+, iCa(2+) and tHb) for which significant differences between analyzers were recorded. No interference of lipemia or methylene blue on CO-oximetry results was found. On the contrary, significant interference for benzalkonium and hemolysis on electrolyte measurements were found, for which the user is notified by an interferent specific flag. Conclusion: Identification of sample errors from pre-analytical sources, such as interferences and automatic corrective actions, along with the analytical performance, ease of use and low maintenance time of the instrument, makes the evaluated instrument a suitable blood gas analyzer for both POCT and laboratory use

Novel applications in the laboratory diagnosis of urinary tract pathology

Urinalysis can be regarded as one of the oldest analyses in the history of laboratory medicine. Performing this set of analyses, a lot of clinically interesting information can be acquired in a fast, reliable and accurate way which may help clinicians in supporting their diagnosis. Besides these advantages, this technique is also characterized by a large inter-observer variability which may lead to analytical bias. Until recently, manual urinary test strip and sediment analysis were characterized by a large variability. Thirty years ago, the implementation of automated urinary test strip and sediment analyzers have led to a better standardized analysis, with an improvement in the analytical variability as a result. With this evolution, also novel parameters become available. In this dissertation, novel applications in the field of urinary test strip and sediment analysis were studied. First, we demonstrated that novel technology is able to generate accurate quantitative information about urinary test strip parameters. Moreover, we found that the introduction of this technology enables laboratory specialists to detect confounding factors in the hemoglobin peroxidase and leukocyte esterase activity. This information can be applied to develop future expert systems that compare the results of urinary test strip and sediment analysis. Furthermore, we developed and validated an algorithm that allows a coarse prediction of urinary osmolality based on urinary creatinine and relative density (urinary test strip) and conductivity (urine sediment). Future studies may elaborate whether this estimated urinary osmolality can be applied to correct for urinary dilution. Finally, we have demonstrated that the parameter renal tubular epithelial cells can be measured in a fast and reliable way using urinary fluoresce flow cytometry and that this parameter has an additional value in the diagnosis of urinary tract infections in adult patients. More specifically, this biomarker adds value in the discrimination between upper and lower urinary tract infection. Whether this parameter has the same performance in other patient populations (e.g. children) can be explored in the future. This doctoral thesis can be regarded as a basis to further evaluate other interesting parameters like ketone bodies on urinary test strips or atypical cells by urinary fluorescence flow cytometry. These parameters are waiting until they are picked up by someone with interest in the field of urine test strip and sediment analysis. The insights that undoubtedly will be acquired in these studies may further be used to expand current available urinary expert systems and improve the laboratory diagnosis of urinary tract pathology

Progress in automated urinalysis

New technological advances have paved the way for significant progress in automated urinalysis. Quantitative reading of urinary test strips using reflectometry has become possible, while complementary metal oxide semiconductor (CMOS) technology has enhanced analytical sensitivity and shown promise in microalbuminuria testing. Microscopy-based urine particle analysis has greatly progressed over the past decades, enabling high throughput in clinical laboratories. Urinary flow cytometry is an alternative for automated microscopy, and more thorough analysis of flow cytometric data has enabled rapid differentiation of urinary microorganisms. Integration of dilution parameters (e.g., creatinine, specific gravity, and conductivity) in urine test strip readers and urine particle flow cytometers enables correction for urinary dilution, which improves result interpretation. Automated urinalysis can be used for urinary tract screening and for diagnosing and monitoring a broad variety of nephrological and urological conditions; newer applications show promising results for early detection of urothelial cancer. Concomitantly, the introduction of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has enabled fast identification of urinary pathogens. Automation and workflow simplification have led to mechanical integration of test strip readers and particle analysis in urinalysis. As the information obtained by urinalysis is complex, the introduction of expert systems may further reduce analytical errors and improve the quality of sediment and test strip analysis. With the introduction of laboratory-on-a-chip approaches and the use of microfluidics, new affordable applications for quantitative urinalysis and readout on cell phones may become available. In this review, we present the main recent developments in automated urinalysis and future perspectives