MODIFIED BROMOPHENOL BLUE DYE BINDING METHOD FOR QUANTITATION OF MICROALBUMINURIA IN DIABETES MELLITUS

Albumin excretion in microalbuminuria range is one of the earliest manifestation of nephropathy, specially in diabetes mellitus. The modified dye binding method using bromo-phenol blue was studied in 27 healthy controls and 54 patients of diabetes mellitus, negative for albuminuria by albustix test. The analytical recovery (99.4 to 104.0%), within run coefficient of variation (0.8 to 0.36%) and day-to-day coefficient of variation (2.39 to 0.82%), for low and higher range were within acceptable limits. The values in controls ranged as follows: urinary albumin concentration (mg/L) 7.7 - 28.4 in 2-hour specimen and 10.3 - 29.2 in overnight specimen; albumin excretion rate (µg/min) 7.8 - 29.7 in 2-hour and 9.2 - 29.6 in overnight specimen; and albumin creatinine ratio (mg/g) 10.6 - 29.6 in 2-hour and 11.9 - 29.6 in overnight specimens. Correlation analysis of various albumin excretion parameters revealed excellent correlation between estimations from overnight and 2-hour samples for albumin-creatinine ratio (r = 1.00) and albumin excretion rate (r=0.96). Equally good correlation was observed between 2-hour albumin-creatinine ratio and albumin excretion rate (r=0.95). In 10 of 54 patients excretion rate was more than 200 µg/min and could have been detected by repeat albustix test. Of the 36 positive for microalbuminuria, 21 had one or more target organ involvement. There was no target organ involvement in 8 patients negative for microalbuminuria. Screening for microalbuminuria by this simple and economic method, using 2-hour albumin-excretion rate or albumin-creatinine ratio could be one of the earliest investigations in diabetic patients.