Indoxyl sulfate as a potential tubular function marker across kidney disease models

Plasma indoxyl sulfate (IS) and its clearance correlate better with tubular injury markers (Kim-1, NGAL) than filtration markers (GFR, creatinine) in chronic nephrectomy rats and chronic/acute ischemic injury (IRI) in mice. Mass spectrometry imaging showed higher cortical but lower medullary IS accumulation in mice, in which proximal tubular transporters were downregulated. In vitro organic anion transporter 1-mediated IS transport decreased post-IRI. Together, plasma IS and its clearance may be used as kidney tubular function markers.