Urinary albumin determination by the immediate bromcresol green method.

It has been demonstrated recently that the reaction of serum samples with bromcresol green (BCG) reagent proceeds in two steps. Albumin is responsible for the immediate reaction while other serum proteins produce the slow reaction. In this paper the immediate BCG reaction has been used for the determination of urinary albumin concentration in patients with proteinuria by a slightly modified method with a primary pH adjustment of the urine and the use of a urine blank. Comparison of the immediate BCG method (y) with Laurell "rocket" technique (x) gave the following equation: y = 17.2 + 1.006x (n = 98; r = 0.99) mg/l. The coefficient of variation (within-day), C.V. (%), ranged between 0.9 and 2.7% depending on the albumin concentration. It is thus possible to carry out rapid, accurate and precise albumin determinations in urine samples using this simple method.