Whole-body protein turnover in metabolically stressed patients and patients with cancer as measured with [15N] glycine.
The whole-body protein synthesis rate (PSR) was measured in 5 control patients (group I) and 38 patients in various clinical states (group II). A single pulse of [15N]glycine was given and the PSR calculated from the 15N enrichment in the urinary ammonia excreted over the next 10 hr. The patients' results fell into three separate groups: group IIa patients were nonstressed and had uneventful recoveries (3.1 +/- 0.6 g prot./kg/day), their PSRs were the same as the control group I, (3.1 +/- 1.0 g prot./kg/day); group IIb patients were stressed, had higher PSRs (6.3 +/- 0.9 g prot./kg/day), one of whom died, and the rest had more complications than group IIa; group IIc patients had very high PSRs (15.4 +/- 6.1 g prot./kg/day), all of whom were seriously ill, and 8 out 12 died; Data are +/- 1 SD. The PSR correlated with the serum glutamate oxaloacetate transferase (SGOT, P less than 0.01). We concluded: (i) [15N]glycine cannot be used to measure the PSR in patients with evidence of liver disease; the results are best interpreted in terms of glycine metabolism; (ii) the "apparent" PSR correlated with clinical status; and (iii) an elevated PSR in a patient with a malignancy is not necessarily due to protein metabolism by the tumor.
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005998:Glycine / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000378:metabolism; D008111:Liver Function Tests; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000378:metabolism*; D009584:Nitrogen / Q000652:urine; D014176:Protein Biosynthesis; D013312:Stress, Physiological / Q000378:metabolism*
D009584:Nitrogen; D005998:Glycine