A Simple Approach to Screening for Microalbuminuria in a Type 1 (Insulin-Dependent) Diabetic Population

Abstract

The reproducibility of albumin concentration in first-morning samples of urine was assessed in 334 insulin-dependent diabetic patients aged 18–60 years. The albumin excretion rate was determined immunoturbidimetrically in three sterile, Albustix-negative, first-morning urine samples submitted over a week. An abnormally high mean value, ≥2 · 5 mg albumin per mmol creatinine (Ua/Uc), was found in 33 patients (9 · 9%). These patients were older (mean 42 vs 34 years, P < 0 · 01), had longer disease duration (18 vs 14 years, P < 0 · 01) and higher HbA₁c values (6 · 8 vs 6 · 3%, P < 0 · 05) than those without microalbuminuria. Although triplicate samples were collected within 7 days, Ua/Uc showed considerable intraindividual variation, with a mean coefficient of variation of 49%. Despite this it was found that Ua/Uc values greater than 1 mg/mmol on the first specimen had a sensitivity of 97% and a specificity of 82% for detecting those with a three-sample mean value greater than 2 · 5 mg/mmol. Thus virtually all those with microalbuminuria (32/33) had a single first-morning result greater than 1 mg/mmol, and in those with a lower ratio microalbuminuria was excluded with more than 99% certainty.