Gas chromatographic and gas chromatographic-mass spectrometric analysis of organic acids in plasma of patients with chronic renal failure.

Apart from increased concentrations of aliphatic dicarboxylic acids and phenolic aromatic acids in plasma from patients with chronic renal failure, there is large elevation of a furanoid acid, 3-carboxy-4-methyl-5-propyl-2- furanpropionic acid, and of hippuric acid. The levels of 3-hydroxy- and 4- hydroxyhippuric acid are also raised. The quantitative results are as follows: furanoid acid in hemodialysis patients, 1.4 +/- 0.6 mg/dl; in healthy individuals, 0.2 +/- 0.1 mg/dl; hippuric acid in hemodialysis patients, 9.8 +/- 6.5 mg/dl; in health individuals, 0.4 +/- 0.5 mg/dl. Both compounds are dialysable, but less effectively than creatinine and urea. The mean elimination rate of the furanoid acid is only 21%.