15N tracer techniques for the differential diagnosis of dwarfism and prediction of growth hormone action in children.
[15N]Glycine in a single oral dose was used to study nitrogen turnover in 18 short children, aged 3-14 yr. On the basis of their serum GH responses to insulin-induced hypoglycemia, the patients were divided into 3 groups: complete GH deficiency (GHD; n = 5); partial GH deficiency (pGHD; n = 6), and children with constitutional growth delay and familial short stature (CGD/FSS; n = 7). The mean 48-h renal excretion of 15N by patients with GHD was 66.09 +/- 14.12% (+/- SD) of the tracer dose. This decreased to 27.64 +/- 5.33% after two injections of 10 IU/m2 GH (P less than 0.001). 15N excretion by patients with pGHD was 47.19 +/- 13.42%, and it decreased after GH injection to 22.69 +/- 4.58% (P less than 0.005). Patients with CGD/FSS had 15N excretion of 37.27 +/- 5.68%, and it did not change in response to GH. The mean protein synthesis rate in GHD patients was extremely low, and it increased after GH injection from 0.99 +/- 0.46 to 3.53 +/- 0.43 g/kg X day. In pGHD patients the protein synthesis rate increased from 2.62 +/- 0.84 to 4.50 +/- 1.09 g/kg X day. The CGD/FSS patients had no change in protein synthesis rate after GH. Our results suggest that studies of the metabolism of [15N]glycine might be of value in predicting responsiveness to GH therapy.
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D004392:Dwarfism / Q000145:classification / Q000188:drug therapy / Q000378:metabolism*; D005260:Female; D005998:Glycine; D013006:Growth Hormone / Q000172:deficiency* / Q000627:therapeutic use; D006801:Humans; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D011506:Proteins / Q000378:metabolism
D009587:Nitrogen Isotopes; D011506:Proteins; D013006:Growth Hormone; D009584:Nitrogen; D005998:Glycine