Determination of plasma albumin concentration in healthy and diseased turtles: a comparison of protein electrophoresis and the bromcresol green dye‐binding method

Background: In reptile medicine, plasma chemistry analysis is widely used for the evaluation of an individual's health status. The standard method for the determination of plasma albumin concentration is protein electrophoresis combined with the determination of total protein concentration, but the bromcresol green (BCG) dye‐binding method is also used. The reliability of the BCG method for the measurement of albumin concentration in reptiles is unknown. Objective: The aim of this study was to compare the plasma albumin values of turtles obtained by protein electrophoresis and the BCG method. Methods: Between March 2008 and September 2008, heparinized plasma samples from 16 clinically healthy and 10 diseased turtles of different species were collected. Plasma albumin concentrations were measured by protein electrophoresis and by the BCG method. The results of the 2 methods were compared using Passing–Bablok regression and Bland–Altman plots. Results: Albumin concentration measured by BCG was weakly correlated with the corresponding protein electrophoretic values in all turtles (r_s=.610, P<.001) and in healthy turtles evaluated separately (r_s=.700, P=.003), whereas in diseased turtles no such correlation was found (r_s=.374, P=.287). The albumin concentration measured with the 2 different methods differed significantly in all turtles (P=.009; Wilcoxon's test) and in healthy turtles (P=.005) but not in diseased animals (P=.241). In the Bland–Altman plot a systematic error was found between the 2 methods in diseased turtles. Conclusion: Measurement of albumin by the BCG dye‐binding method may lead to inaccurate results for plasma albumin concentration, especially in ill turtles. Therefore, for health assessment in turtles, albumin should be measured by protein electrophoresis.