Studies on protein and nitrogen metabolism in nephrotic syndrome using 15N-labelled glycine and urea

Administering 15N-labelled glycine, 15 N incorporation into serum albumin and its excretion into urine and feces, together with nitrogen balance were investigated in 3 nephrotic and 2 normal adults. Furthermore, 15N-labelled urea was injected into a nephrotic adult and a glomerulonephritic adult, both advanced in azotemia and treated on low protein diet, and a normal subject on a normal diet, to examine the amounts of 15N incorporation into serum albumin. In the 3 nephrotic patients whose nitrogen balance was almost maintained, incorporation of 15N-glycine into serum albumin has been proved greater than in the normal subjects. In any of the above patients, 15N excretion into urine was less than in the normal subjects. Fecal 15N excretion was 2.0--2.5 % of the doses, indicating that approximately 98 % of 15N-glycine was absorbed. In the nephrotic patients, 15N incorporation into serum albumin examined by 15N-labelled urea administration was more accelerated than in the glomerulonephritic patients and was negligible in the control subject on a normal diet.