Correlation of a colorimetric and a HPLC method for the determination of serum hippuric acid concentrations in uremia.

Hippuric acid has been recognized as a potential marker of uremic toxicity in chronic renal failure. However, in most studies, serum hippuric acid concentrations have been determined by sophisticated methods, such as high-performance liquid chromatography. The present study was undertaken to evaluate whether the less complicated colorimetric determination method could replace such methods. Based on 21 different samples, the results obtained by both methods appeared to be correlated to each other in a highly significant way (total hippuric acid: r = 0.99, p less than 0.001; free hippuric acid; r = 1.00, p less than 0.001). Mean total and free hippuric acid concentrations and mean percent protein binding, obtained with both determination methods, were also identical. It is concluded that both the colorimetric method and high-performance liquid chromatography are equally reliable for the study of the concentration of hippuric acid in uremic serum and of its importance as a marker of the clinical and biochemical epiphenomena of uremic toxicity.