Screening for microalbuminuria in type 2 diabetic patients: the evaluation of a dipstick test in general practice

To evaluate the Micral test, a semiquantitative dipstick test, in a general practice setting, 317 Type 2 diabetic patients completed a screening for microalbuminuria by means of the Micral test as well as immuno-nephelometry with the Disc 120 immuno-nephelometer (Hyland, Nivelles, Belgium). Data were collected in 10 general practices performing the Nijmegen Monitoring Project. At a regular check-up each Type 2 diabetic patient was asked to collect first morning urine samples on three consecutive days. The sensitivity of the Micral test was 67%, the specificity 93%. Between the practices the sensitivity ranged from 58% to 81%, the specificity from 87% to 95%. Microalbuminuria, defined as a mean urine albumin concentration > or = 20 mg I-1 by nephelometry on three consecutive days, was found in 66 patients (21%). The first Micral test correctly picked out these patients with microalbuminuria in 70% of the cases and in 90% those patients without microalbuminuria. The diagnostic performance of the Micral test was further proved by a Receiver Operating Characteristic (ROC) curve. The Area Under the Curve (AUC) of the Micral test was 0.84 (95% CI 0.78-0.90). Micral test results of 0 and 10 should be regarded as negative.