Protein and Amino Acid Metabolism in Nephrotic Syndrome

Serum concentrations of amino acids were measured in 10 nephrotic patients either with neutral or slightly positive nitrogen balance. Also, 15N incorporation into serum albumin, its excretion into urine and feces was measured by giving 50% 15N-glycine into 3 nephrotic patients and 2 normal subjects. Further more, 15N incorporation into serum albumin and its excretion into urine was examined in a renal failure patient advanced from nephrotic syndrome and another renal failure patient advanced from chronic glomerulonephritis and a normal subject, by intravenously administrating 2g of 50% 15N urea. 15N incorporation into serum albumin with 15N-glycine administration in nephrotic patients was twice the normal. However, the amount of 15N incorporated into albumin in nephrotic patients rapidly decreased, and the level in albumin was lower than the normal in ten days. The average exretion rate of 15N into urine 7 days after 15N-glycine administration was 34.2% in nephrotic patients and 45.8% in the normal, suggesting greater recycling of 15N into protein synthesis in the patient. The serum concentrations of amino acids in 10 nephrotic patients were comparable to those of normal subjects and the concentrations of alanine, glutamine and arginine were significantly higher than the normal. 15N incorporation into serum albumin examined by 15N-urea administration in a renal failure patient advanced from nephrotic syndrome was greater than in one advanced from glomerulonephritis, and the normal was negligible.