Sex-Dependent Determinants of Uremic Toxicity in Chronic Kidney Disease

Chronic kidney disease (CKD) is characterized by the progressive accumulation of uremic toxins (UTs), which contribute to systemic complications, increased cardiovascular risk, and disease progression. Epidemiological and experimental evidence demonstrate pronounced sex differences in CKD progression and outcomes, yet the mechanisms underlying sex-specific uremic toxicity remain unclear. This review synthesizes current knowledge on sex differences in the origin, metabolism, transport, and biological effects of UTs, with a focus on sex-dependent regulatory mechanisms along the gut–liver–kidney axis. Sex hormones influence key determinants of toxin handling, including gut microbiota composition, hepatic enzyme activity, plasma protein binding, membrane transporter expression, and intracellular signaling pathways. Together, these factors regulate systemic toxin exposure and tissue susceptibility to injury. CKD also disrupts endocrine homeostasis, creating bidirectional interactions between hormonal regulation and toxin accumulation. Experimental and limited clinical evidence suggest that sex may influence circulating toxin profiles and susceptibility to toxin-associated complications. Collectively, sex is an important modulator of uremic toxicity, with sex hormones mediating at least part of the sex differences. A sex-informed framework may improve fundamental understanding through mechanistic studies and future clinical research may help clarify its relevance for biomarker development and support the development of personalized therapeutic strategies for CKD.