Simplified screening for microalbuminuria

Background: Screening for microalbuminuria is increasingly advocated as a way to diagnose early renal involvement in diabetes and other diseases. It usually entails the use of a radioimmunoassay that is expensive and not always readily available. Objective: To assess the efficacy of three simple and inexpensive tests for ruling out microalbuminuria. Design: Cross-sectional study. Setting: Outpatient clinics. Patients: 221 patients from primary care clinics and a diabetes clinic. Measurements: Random urine specimens were tested for albumin by using Micral-Test immunoassay strips (Boehringer Mannheim, Mannheim, Germany) and for protein by using sulfosalicylic acid testing and impregnated dipsticks (Chemstrips, Boehringer Mannheim). Radioimmunoassay for albumin was used for all specimens as standard for comparison. Results: When less than 20 mg/L was considered the upper limit of normal for albumin concentration, Micral-Test, sulfosalicylic acid testing, and Chemstrips had negative predictive values of 99%, 95%, and 96%, respectively. Seventy-four specimens tested negative on both sulfosalicylic acid and Chemstrips; the negative predictive value of these two tests combined was 99%. Conclusions: The combination of sulfosalicylic acid testing and Chemstrips was as good as and less expensive than Micral-Test in ruling out microalbuminuria.