Indoxyl sulfate: clinical implications for anemia management in chronic kidney disease

Abstract

Purpose of review – This review examines the role of indoxyl sulfate, a gut-derived uremic toxin, in the development of anemia in chronic kidney disease. It dissects the cellular and biochemical mechanisms through which indoxyl sulfate suppresses erythropoietin production, disrupts iron metabolism, and promotes oxidative stress and inflammation. Recent findings – Indoxyl sulfate interferes directly with the hypoxia-inducible factor pathway, thereby reducing the transcriptional activation of erythropoietin. In parallel, indoxyl sulfate-induced oxidative stress damages red blood cells and accelerates premature cell death, while its stimulation of pro-inflammatory pathways further downregulates erythroid progenitor cell function. Therapeutic strategies such as dietary protein modulation, gut microbiota interventions, oral adsorbents, and enhanced dialysis modalities have shown promise in lowering indoxyl sulfate levels and, consequently, improving erythropoietin responsiveness and iron homeostasis in chronic kidney disease patients. Summary – The review synthesizes evidence from clinical and experimental studies that position indoxyl sulfate as a central yet underappreciated mediator of anemia in chronic kidney disease. Indoxyl sulfate establishes a vicious cycle that exacerbates anemia and contributes to erytropoiesis-stimulating agent hyporesponsiveness. The article advocates for targeted interventions aimed at reducing indoxyl sulfate burden, which could transform anemia management in chronic kidney disease and pave the way for personalized treatment strategies.