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 TI 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.