A chemical test strip to determine low concentrations of albumin and creatinine in urine

The performance of a new test strip for determining urine albumin concentration was evaluated. The test is based on formation of a strongly colored blue complex between albumin and the high-affinity dye bis(3':3 "-diiodo-4',4 "-dihydroxy-5':5 "-dinitrophenyl)-3,4,5,6-tetrabromosulfonephthalein. Color reactions were read with a reflectometer. At a cutoff of 30 mg/L, sensitivity was 0.97 specificity 0.83, positive predictive value 0.73, and negative predictive value 0.98 which allowed detection and exclusion of microalbuminuria. Estimation of creatinine concentration with a second reactive pad gave an albumin/creatinine ratio comparable to the ratio obtained with reference methods in 87.8% of cases, allowing elimination from further investigation of increased albumin concentrations simulated by low-level diuresis. It is suggested that this combination test strip be used for large-scale screening for microalbuminuria.