Protein loading test before and after kidney donation.

Renal response to a 60 g protein load was investigated in 33 normal subjects in terms of creatinine clearance and urinary protein excretion. The test was repeated in 10 of these subjects six months after donor nephrectomy. Creatinine clearance and urinary protein excretion increased significantly one and two hours after ingestion of the protein load (in the form of casein mixture); the change in urinary protein excretion correlated significantly with the change in creatinine clearance (p less than 0.0001). Plasma urea, calcium, and phosphate concentrations increased after protein ingestion, while plasma creatinine and uric acid decreased. Six months after donor nephrectomy the creatinine clearance had decreased but baseline protein excretion had increased. The pre-nephrectomy renal response to protein ingestion (i.e. increase in creatinine clearance and urinary protein excretion) did not predict creatinine clearance of the kidney after donor nephrectomy. After donor nephrectomy, the single kidney was able to increase creatinine clearance after a protein load, although qualitatively the response was different from that obtained with two kidneys in situ.