Osmoregulation Performance and Kidney Transplant Outcome

International audienceBackground Kidney transplant recipients have an impaired ability to dilute urine but seldom develop baseline hyponatremia before ESRD. Although hyponatremia is a risk factor for adverse events in CKD and in kidney transplant recipients, it remains unclear whether subtler alterations in osmoregulation performance are associated with outcome. Methods We studied a single-center prospective cohort of 1258 kidney transplant recipients who underwent a water-loading test 3 months after transplant to determine osmoregulation performance. Measured GFR (mGFR) was performed at the same visit. A group of 164 healthy candidates for kidney donation served as controls. We further evaluated the association of osmoregulation performance with transplantation outcomes and subsequent kidney function. Results Unlike controls, most kidney transplant recipients failed to maintain plasma sodium during water loading (plasma sodium slope of −0.6±0.4 mmol/L per hour in transplant recipients versus −0.12±0.3 mmol/L per hour in controls; P