Side-room tests to screen for microalbuminuria in diabetes mellitus.
Three side-room tests (latex bead immunoagglutination test, LBT; 25% sulphosalicylic acid test, SST; microalbutest, MAT) for the detection of microalbuminuria in diabetics are described and their screening potential and practicability assessed. One hundred insulin-dependent diabetics attending a diabetic clinic provided an early morning urine sample (Albustix-negative) which was subjected to each of the three tests, and urinary albumin concentration (UA) was assayed by RIA. Tests were assessed in random order by two trained operators using a semiquantitative grading scale with 100% concordance between 10 observers. All test results greater than or equal to trace +ve were sufficiently sensitive (sensitivity greater than or equal to 90%) in detecting UA greater than 15 mg/l, but MAT exhibited a significantly reduced specificity (69%) and positive predictive value (58%). For a reference UA greater than 30 mg/l, LBT and SST results greater than or equal to trace +ve and MAT results greater than or equal to +ve showed a sensitivity of 100%, a specificity greater than 85% and a positive predictive value greater than 60%. Reagent shelf-life was shortest with LBT. SST involved centrifugation or filtration. Technical skill required was highest with LBT and lowest with MAT. Costs were slightly higher with LBT than SST and were not available for MAT.