Sex steroids levels in chronic kidney disease and kidney transplant recipients: associations with disease severity and prediction of mortality

ObjectiveOur objective was to characterize and evaluate prognostic implications of circulating sex steroids in patients at different stages of chronic kidney disease (CKD). DesignProspective observational cohort study. PatientsWe prospectively recruited patients with CKD III-IV, undergoing chronic dialysis and kidney transplant recipients (KTR) from a single centre in 2003-2004. MeasurementsTwo stored samples taken 3months apart were analysed for sex hormones using liquid chromatography/tandem mass spectrometry, and the mean of the two was used for analysis. We also measured novel biomarkers troponin T and NT-proBNP. Patients were followed until death, transplant or 30 June 2013, and survival analysis performed. ResultsIn males, but not in females, both testosterone (P=0003) as well as oestradiol (P<002) levels were lowest in dialysis patients and highest in KTR. Over a median follow up of 85years (interquartile range 38-92), 52 men (36%) died and 24 (17%) received a kidney transplant. In Cox proportional hazards regression up to 96years, an increase in total testosterone of 1nmol/l was associated with a 98% (95% confidence interval 31-163) decrease in mortality independent of age, body mass index, stage of renal disease and circulating levels of NT-proBNP or troponin T. By contrast, sex steroid levels were not associated with mortality in females. ConclusionsTestosterone levels differ across stages of kidney disease and low testosterone levels predict mortality in males, independent of established and novel predictors of mortality.