Glucose Interference in Serum and Urine Samples with Various Creatinine Concentrations Measured by the Jaffe Kinetic Method.

Background: The effect of glucose interference on creatinine measurement by Jaffe kinetic method differs between serum and urine specimens. We investigated the effects of creatinine concentration and specimen dilution on glucose interference with urine creatinine measurement. Methods: Leftover serum and urine specimens were collected and stored at -20°C until study. Serum specimens were mixed to make 5 glucose concentrations ranging from <5.6 to 27.8 mmol/L, each group consisting of 5 levels of creatinine concentration ranging from <45 to 354 µmol/L. Urine specimens were divided into 5 groups of creatinine concentration ranging from <1,769 to >7956 µmol/L, each sample was spiked with glucose powder to produce 5 aliquots with glucose concentrations ranging from 0 to 666 mmol/L. Urine samples were automatically diluted 1:20 before analysis. Percent interference of creatinine measurement by Jaffe kinetic method was calculated using enzymatic method as the reference. Results: A total of 148 serum samples and 335 urine samples were analyzed. In serum, glucose interference with Jaffe creatinine measurement was found if creatinine concentrations were 177 µmol/L or less, corresponding to 3,540 µmol/L or less in urine specimens prior to 1:20 dilution. The degree of interference was greater when glucose concentration was higher or creatinine concentration was lower. Conclusions: When creatinine concentration and specimen dilution were considered, the effects of glucose interference on Jaffe creatinine measurement were similar in serum and urine specimens, and was found when creatinine concentrations in serum or diluted urine were 177 µmol/L or less.

Comparison of the complete filtration method using an automated feces analyzer with three manual methods for stool examinations.

Conventional diagnostic techniques using manual methods for stool examination have important limitations. Hence there is a need for improved technologies in routine clinical practice. This study aimed to compare detection rates, agreements, and diagnostic performances for stool examinations in all parameters of the complete filtration method using the Sciendox Feces Analysis System-50 automated feces analyzer with three manual methods, the direct smear, Kato's thick smear, and formalin ethyl concentration techniques. The 252 routine stool samples were examined for parasites, white blood cells (WBCs), red blood cells (RBCs), fat globules, and yeast cells using the four methods indicated above, and the complete filtration detection rates, Cohen's kappa (κ), and diagnostic performances were evaluated and compared. The detection rates of RBCs, fat globules, and yeast cells examined by the complete filtration automated method were comparable to the manual methods, but the detection rates of parasites and WBCs were significantly lower. Most methods detected the same seven parasite species, Ascaris lumbricoides, hookworm, Trichuris trichiura, Strongyloides stercoralis, Entamoeba histolytica/dispar, Blastocystis spp., and Giardia intestinalis. Pairwise agreements between the complete filtration and other methods were good to very good for all parameters showing κ values of 0.74 to 0.89. The diagnostic performances against the combined results showed complete filtration method sensitivities of 70%, 81.82%, 77.27%, 100%, and 95% for parasites, WBCs, RBCs, fat globules, and yeast cells, respectively, while the complete filtration negative predictive values (NPVs) and accuracies showed higher than 95% for all parameters. The complete filtration method using the automated feces analyzer showed high NPVs and accuracies, and good agreements with the three tested manual methods for stool examination in all parameters.

A comparison of automated urine analyzers cobas 6500, UN 3000-111b and iRICELL 3000 with manual microscopic urinalysis.

OBJECTIVES: Microscopic examination is essential in urine analysis. This is a simple way to collect informative data but it is also labor-intensive, time-consuming, and requires experienced staff for accurate results and interpretation. Several automated urine analyzers have been introduced for urine analysis in medical laboratories. The aim of this study was to assess and compare the performance of the most common three automated urine analyzers, Cobas 6500, UN3000-111b and iRICELL 3000. DESIGN: and Methods: A total of 100 routine urine samples were used in the study. Results from the three machines were compared with the routine procedure results including physical, chemical and sediment analysis. RESULTS: There was good correlation of urine physical and chemical analyses between the three analyzers with an overall concordance level of more than 80%. For sediment analysis, the degree of concordance between manual analysis and the three instruments was very good to good for white blood cells, red blood cells and epithelial cells, and moderate for bacteria. There were fair to good agreements between manual microscopy and the three instruments, Cobas 6500, UN3000-111b and iRICELL 3000, for casts (Cohen's kappa 0.42, 0.38 and 0.62, respectively). CONCLUSIONS: The three automated urine analyzers showed similar performances and good correlation with manual microscopy. The results of this study indicate that automated urine analyzers could be used for initial urine testing to reduce high workloads and to save time, but manual microscopic analysis by experienced staff is still necessary to classify urine sediments for confirmation, especially in pathologic specimens.