The effects of growth hormone on protein metabolism in adult growth hormone deficient patients.
OBJECTIVE
Growth hormone treatment given to adult growth hormone deficient patients leads to an increase in lean body mass by an unknown mechanism. The aim of this study was to investigate the actions of growth hormone treatment on protein metabolism in adult growth hormone deficient patients.


METHODS
Double-blind, placebo controlled trial of recombinant human growth hormone (0.018 U/kg/day for 1 month followed by 0.036 U/kg/day for 1 month) with isotopic whole body protein turnover studies at 0 and 2 months.


METHODS
Eighteen adult growth hormone deficient patients (nine male, nine female of mean age 46.6 (range 30-56).


METHODS
Whole body isotopic leucine turnover using L-1-13C-leucine measuring leucine Ra (a measure of protein degradation), non-oxidative leucine Rd (a measure of protein synthesis) and leucine oxidation rate.


RESULTS
Lean body mass (P < 0.02), circulating insulin-like growth factor I (P < 0.01) and insulin (P < 0.02) were significantly increased at 2 months in the treatment group but there was no change in the placebo group. When expressed in relation to body weight, leucine Ra and non-oxidative leucine Rd increased (P < 0.01) and leucine oxidation decreased (P < 0.02) after 2 months growth hormone treatment. When expressed in relation to lean body mass non-oxidative leucine Rd increased (P < 0.02) and leucine oxidation decreased (P < 0.02) but there was no significant change in leucine Ra after 2 months growth hormone treatment. In the placebo group there were no significant changes in leucine metabolism expressed as lean body mass or body weight after 2 months. changes in leucine metabolism expressed as lean body mass or body weight after 2 months.


CONCLUSIONS
These results indicate that the increase in lean body mass resulting from growth hormone treatment in adult growth hormone deficient patients is due to an increase in protein synthesis.
Russell-Jones
D L
DL
Division of Endocrinology and Medicine, United Medical School, London, UK.
Weissberger
A J
AJ
Bowes
S B
SB
Kelly
J M
JM
Thomason
M
M
Umpleby
A M
AM
Jones
R H
RH
Sönksen
P H
PH
D000328:Adult; D001835:Body Weight / Q000187:drug effects; D004311:Double-Blind Method; D005260:Female; D006130:Growth Disorders / Q000188:drug therapy* / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism / Q000627:therapeutic use*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000627:therapeutic use
D007328:Insulin; D011506:Proteins; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D007930:Leucine