Abstract
A rapid assay for serum indoxyl sulfate was developed using internal-surface reversed-phase high-performance liquid chromatography (ISRP-HPLC). The identification of indoxyl sulfate was confirmed by secondary ion mass spectrometry and UV spectrometry. By using ISRP-HPLC, the serum level of indoxyl sulfate can be directly analyzed from serum samples, without deproteinization.
The serum level of indoxyl sulfate was quantitated in 80 chronic hemodialysis patients. The serum level of indoxyl sulfate before hemodialysis in the hemodialysis patients, 32.6μg/ml, was markedly increased compared with that in healthy subjects, 0.5μg/ml, and showed weak but significant correlation with duration on hemodialysis, serum creatinine, and serum β2-microglobulin. The serum level of indoxyl sulfate in the hemodialysis patients was 25.7μg/ml after hemodialysis. Protein (albumin) binding of indoxyl sulfate before and after hemodialysis was 89% and 84%, respectively.
Equilibrium dialysis demonstrated that indoxyl sulfate inhibited the albumin binding of salicylate and that 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid inhibited the albumin binding of indoxyl sulfate.
Indoxyl sulfate which was bound to serum albumin, could not be easily removed from blood by hemodialysis, and therfore was markedly accumulated in uremic serum as an inhibitor of drug-binding.
