March 12, 2025

Urine output after kidney transplantation hints at who may have good transplant outcomes

Recent research shows that kidney transplant recipients may be at greater risk of losing their new kidney if they experience only a small amount of urine excretion in the first day after their transplantation.  

Kidney transplantation is the ideal treatment for people experiencing kidney failure. However, sometimes the transplantation is unsuccessful, and the new transplanted kidney either experiences a delay in function or fails entirely (graft loss). Some initial evidence suggests that the amount of urine a patient excretes early after kidney transplantation is associated with subsequent kidney transplant survival. To explore this phenomenon in more detail, Dr. Steven Morrison and colleagues followed 991 patients in Atlantic Canada who received a kidney transplant between 2006 and 2019. 

The results show that patients who had low urine output (defined as less than 1,000 mL) in the first day after their kidney transplant had a 42x higher chance of their new kidney experiencing a delay in functioning and a 4x higher risk of their transplanted kidney failing completely over time, compared to patients with greater urine output. Over a median follow up period of 8.3 years, 17 per cent of patients with low urine output following transplantation went on to experience graft loss, whereas only 8 per cent of patients with high urine output did. Remarkably, urine output was a stronger risk factor for graft loss than other well-known risks, including warm and cold ischemia time, DCD donor status, and dialysis modality.  

The authors note that this study was not designed to explore whether interventions aimed at improving urine output—such as diuretics, vasopressors, or intravenous fluid—would impact transplantation outcomes, and suggest that future studies could investigate this possibility.