Reliability of albumin bromocresol green colorimetric method and clinical impact

Measuring plasma albumin is a common and important laboratory test. We compared the results obtained with the bromocresol green (BCG) colorimetric, immunoturbidimetric (IT), and capillary electrophoresis (CE) methods and evaluated the clinical reliability of the colorimetric test. Samples from 320 patients including 227 patients with hypoalbuminemia (albumin levels <35 g/L) were analyzed. Results were compared between different patient groups. The BCG method indicated significantly higher plasma albumin levels than the CE and IT methods, especially in patients with elevated C-reactive protein, alpha-1 globulin (a1G), and alpha-2 globulin (a2G) values. A significant proportion of patients with mild hypoalbuminemia tested using the BCG method (alb_BCG) and were classified as severely hypoalbuminemic (albumin <20 g/L) when switching to the CE or IT method (alb_CE and alb_IT). These patients had elevated a1G and/or a2G levels. This change of result implied an additional indication for albumin replacement therapy. The BCG method significantly overestimates albumin levels in patients with inflammation and hypoalbuminemia, which may lead to inappropriate therapeutic decisions.