Microalbuminuria in Diabetes: A Population Study of the Prevalence and an Assessment of Three Screening Tests

A single observer reviewed 842 of the 917 known diabetic patients registered with 40 GPs in the Poole area. A midstream urine specimen was tested for proteinuria using Albustix (Ames) and cultured to detect bacterial infection. After the first 3 months of the survey, the aliquot of this specimen was frozen for later determination of the random albumin/creatinine ratio (R-Alb/Creat). Patients were requested to submit a timed overnight urine collection for estimation of urinary albumin excretion rate (AER). Of the 842 patients reviewed, 493 (59 %) submitted timed overnight urine collections; 43 were excluded because of urinary infection and/or proteinuria. One hundred and thirty-three (30 %) of 450 diabetic patients were found to have microalbuminuria, although only 31 (7 %) had an AER >30 μg/min. Six hundred and seven urine samples were collected for R-Alb/Creat but 68 were excluded because of infection and/or proteinuria; in 10 further samples urinary creatinine was not measured. Two hundred and four (38 %) of 532 diabetic patients were found to have an elevated R-Alb/Creat. There was a significant correlation between AER and R-Alb/Creat (r=0.32, p 30 μg/min was assessed. An ON-Alb/Creat > 2.0 mg/mmol was the optimal screening test (sensitivity 96 % and specificity 99.7 %). The proportion of diabetic patients with an AER in the range indicating a high risk of developing nephropathy is small. If an ON-Alb/Creat > 2 mg/mmol had been used, 84 % of diabetic patients in this survey would not have been identified as being at risk. In future, this will enable further assessment to be concentrated on the high risk group.