Multicenter evaluation of the Micral-Test II test strip, an immunologic rapid test for the detection of microalbuminuria.

OBJECTIVE: To assess the performance of the Micral-Test II immunologic test strip for the detection of microalbuminuria, a multicenter evaluation in eight European study sites was performed. RESEARCH DESIGN AND METHODS: Using both the Micral-Test II test strip and the routine method for the determination of albumin concentration, we investigated 2,228 urine samples from diabetic patients. Additionally, interperson variability, color stability, and possible interfering factors (temperature, pH, leucocyturia, erythrocyturia, and drugs) were tested. RESULTS: For a cutoff concentration of 20 mg/l with respect to the routine methods, a sensitivity of 96.7% and a specificity of 71% were calculated for the Micral-Test II test strip. The negative predictive value was 0.95, and the positive predictive value was 0.78, with a prevalence of positive samples (laboratory method) of 52%. The interperson variability of color interpretation showed 93% concordant readings. The interference study showed an influence of oxytetracycline, leading to higher readings. There was no interference from pH. A sample temperature of < 10 degrees C led to lower readings. In the case of samples with massive leucocyturia and erythrocyturia that may delete the chromatographic process, waiting an additional 1-2 min is needed before reading. CONCLUSIONS: The results of the multicenter evaluation show that the Micral-Test II test strip permits an immediate and reliable semiquantitative determination of low albumin concentrations in urine samples with an almost user-independent color interpretation.

[Clinical importance of sampling method in leucocyturia (author's transl)]. / Klinische Bedeutung der Probengewinnung bei Leukozyturie.

The clinical importance of the method of obtaining a urine sample (spontaneous vs. catheter and midstream specimens) was investigated in 507 in-patients. Whereas leucocyturia was demonstrated with the Cytur-Test on spontaneous urine from 105 patients, only 30 out of 89 of these patients showed leucocyturia in catheter or midstream specimens one to three days later. All 30 positive cases were found to have a disease state which causes leucocyturia. A direct comparison between spontaneous urine and midstream or catheter urine taken at the same time in 68 patients showed a leucocyturia in 20 cases in spontaneous urine which could not be confirmed in the midstream or catheter urine. This drastic difference shows the importance of the method of obtaining specimens in estimating leucocyturia.

[Rationalization of urine analysis while maintaining diagnostic accuracy (author's transl)]. / Rationalisierung im Urinlaboratorium ohne Verzicht auf diagnostische Sicherheit.

Screening 720 morning urinary samples for WBC, RBC and protein by test-strip, the number of subsequent microscopic examinations of urinary sediment was reduced to about half, without missing any significant number of clinically significant findings (4.4%). On the other hand, a large number (21.3%) of cases with obviously false-negative sediment findings were revealed. These were largely due to lysis of WBC and RBC, as well as poorly standardized methods of examining urinary sediment. But they could also have been due to differences in subjective criteria employed by the technicians. Our results indicate that using test-strips for screening, clinical routine examination can be rationalized, taking about half the time needed for sediment examination, with more potentially significant findings being discovered than missed.

[Reference values for a new alpha-amylase determination in serum and urine (author's transl)]. / Referenzwerte für eien neue alpha-Amylase-Bestimmung im Serum und Urine.

Reference values for a new alpha-amylase estimation using maltoheptaose as substrate were determined in 251 healthy men and women in serum at 25 degrees C and at 30 degrees C and in urine at 25 degrees C. Sex dependency was not demonstrable. The following reference ranges are suggested: 30-100 U/l in serum at 25 degrees C, 40-130 U/l in serum at 30 degrees C, and 500 U/l in urine at 25 degrees C. In addition reference values for the relative percentual amylase-creatinine clearance (25 degrees C) of 0.25-4% and for amylase activity per mg creatinine (urine 25 degrees C) of 0.02-0.25 U/mg creatinine are suggested.