Subclinical elevation of urinary albumin excretion early in the course of insulin-dependent diabetes has been shown to predict later clinical proteinuria. An agglutination test (Three-drop Albutest) to detect these lesser degrees of albuminuria has been developed. Rabbit anti-human albumin antiserum is immobilized on latex beads. In the presence of human albumin and additional antiserum in solution, a visible precipitate appears. Concentrations of solid and liquid phase antiserum have been adjusted to detect urinary albumin concentrations ranging between 2.5 and 17 mg/dl, undetectable by a standard clinical method (Albustix, Ames Company, Miles Laboratories Ltd, Stoke Poges, Slough, Bucks, England). The test is specific for albumin, failing to cross-react with other plasma proteins present in urine or with bovine serum albumin. It is simple to perform and is read within 5 min.
This test should find a place in the early detection of diabetics with subclinical albuminuria and in monitoring the success of attempts to reverse this risk factorfor clinical diabetic nephropathy.
