Indican or indoxyl sulfate is primarily known as a uremic toxin and metabolite of L-tryptophan, affecting the progression of chronic kidney disease and cardiovascular disease. Indoxyl sulfate is produced through a series of reactions involving intestinal bacteria and the liver. L-tryptophan is metabolized by gut bacteria to indole, transported to the liver where CYP2E1 converts it to indoxyl, then sulfated by sulfotransferases, forming indoxyl sulfate. Indoxyl sulfate is highly protein-bound in plasma, >90% attached to proteins, mainly albumin, limiting removal by hemodialysis and resulting in accumulation in patients with impaired kidney function. In healthy individuals, indoxyl sulfate is cleared efficiently via tubular secretion, but in CKD, reduced renal clearance leads to elevated plasma levels. As a uremic toxin, indoxyl sulfate speeds the progression of CKD by stimulating glomerular sclerosis and renal interstitial fibrosis. It induces oxidative stress, inflammation, and apoptosis in renal tubular cells, promoting kidney damage. Indoxyl sulfate acts as a cardiotoxin, impairing endothelial function, inhibiting angiogenesis, and increasing the risk of vascular disease and atherosclerosis in CKD patients. It has been implicated in bone disease, muscle wasting, and potential neurotoxicity, complicating the clinical picture in patients with advanced kidney disease. AkrivisBio’s Indican Assay is a simple sensitive means of quantifying indican with a sensitivity below 0.5 mg/dl.
