Utility of micral test strips in screening for microalbuminuria

Objective.-To evaluate the clinical utility of Micral strips for detection of microalbuminuria. Design.-One hundred three urine samples were tested by Micral strips for the presence of microalbuminuria, and the results were compared with the immunonephelometric method. Setting.-Endocrine diabetes clinic in a university-affiliated outpatient facility and the associated clinical laboratory. Patients.-Sixty-seven, 24-hour urine samples were obtained from 64 patients with diabetes. Thirty-six urine samples were obtained from normal controls; 22 of these were 24-hour samples and 14 were overnight samples. Main Outcome Measore.-Concordance of results obtained by the two methods for the presence or absence of microalbuminuria. Results.-All 36 control subjects and 44 urine samples from diabetic patients had normal albumin excretion (< 15 mg/24 h) by the immunonephelometric method. Seventy-eight of these were correctly identified as negative by Micral strips, giving a specificity of 97.5%. There were 23 samples with albumin excretion of more than 16 mg/24 h. Sixteen of these were correctly identified, giving a sensitivity of 69.5%. There were 16 samples with albumin excretion of 30 mg/24 h or more; 14 of these were correctly identified by Micral strips, and two were false negatives, giving a sensitivity of 87.7%. However, when urine samples with albumin concentrations of less than 11 mg/L were excluded, the Micral strips correctly read 21 out of 23 samples, giving a sensitivity of 91.3%. Conclusions.-The specificity of Micral strips for detection of albuminuria in 24-hour urine samples is high (97.5%), but the sensitivity is low, ranging from 69.5% to 87.7%. The sensitivity was greatly improved when urine samples with albumin concentrations of less than 11 mg/L were excluded.