Renal outcome 25 years after donor nephrectomy

The extended outcome after kidney donation has been a particular concern ever since the recognition of hyperfiltration injury. Few published reports have examined donor renal outcome after 20 years or greater. Kidney transplantation has been performed at the Cleveland Clinic Foundation since 1963, at which there is extensive experience with live donor transplantation. We assess the impact of donor nephrectomy on renal function, urinary protein excretion and development of hypertension postoperatively to examine whether renal deterioration occurs with followup after 20 years or greater.

From 1963 to 1975, 180 live donor nephrectomies were performed at the Cleveland Clinic. We attempted to contact all patients to request participation in our study. Those 70 patients who agreed to participate in the study were mailed a package containing a 24-hour urine container (for assessment of creatinine, and total protein and albumin), a vial for blood collection (for assessment of serum creatinine) and a medical questionnaire. All specimens were returned to and processed by the Cleveland Clinic medical laboratories. Blood pressure was taken and recorded by a local physician. A 24-hour creatinine clearance and the Cockcroft-Gault formula were used to estimate renal function, and values were compared with an age adjusted glomerular filtration rate for a solitary kidney.

Mean patient followup was 25 years. The 24-hour urinary creatinine clearance decreased to 72% of the value before donation. For the entire study cohort serum creatinine and systolic blood pressure after donation were significantly increased compared with values before, although still in the normal range. The overall incidence of hypertension was comparable to that expected in the age matched general population. There was no gender or age difference (younger or older than 50 years) for 24-hour urinary creatinine clearance, or change in serum creatinine before or after donation. Urinary protein and albumin excretion after donation was significantly higher in males compared with females. There were 13 (19%) subjects who had a 24-hour urinary protein excretion that was greater than 0.15 gm./24 hours, 5 (7%) of whom had greater than 0.8. No gender difference was noted in blood pressure, and there were no significant changes in diastolic pressure based on gender or age.

Overall, renal function is well preserved with a mean followup of 25 years after donor nephrectomy. Males had significantly higher protein and albumin excretion than females but no other clinically significant differences in renal function, blood pressure or proteinuria were noted between them or at age of donation. Proteinuria increases with marginal significance but appears to be of no clinical consequence in most patients. Patients with mild or borderline proteinuria before donation may represent a subgroup at particular risk for the development of significant proteinuria 20 years or greater after donation. The overall incidence of proteinuria in our study is in the range of previously reported values after donor nephrectomy.