To predict microalbuminuria easily in the diabetic outpatient clinic, we determined the range of albumin concentrations in the single-void first morning urine in 1090 healthy subjects of age 6-11 by the modified turbidimetry immunoassay (TIA) method, which uses 96-well microplates and a microplate reader to perform the assay quickly and conveniently. As the correlation coefficient of albumin concentration by the TIA uncorrected for creatinine versus corrected for creatinine was r = 0.79 (P less than 0.005), the values uncorrected for creatinine were used. When the distribution of values from 1090 healthy young children was simulated by using the chi-square test (k = 1), the 95% confidence interval was 0-18 micrograms/ml.