Administration of recombinant human growth hormone on alternate days is sufficient to increase whole body protein synthesis and lipolysis in growth hormone deficient adults

OBJECTIVE At present, the duration of the effect of recombinant human growt h hormone (rhGH) on the rates of protein synthesis and lipolysis in GH defi cient (GHD) adults is unknown. This study was designed to establish the fre quency of rhGH administration necessary to provide the beneficial metabolic effects of the hormone in GHD adults. DESIGN AND PATIENTS Two different studies (A and B) were performed in two g roups of five GHD men. In study A, whole body protein and lipid kinetics wa s determined in the basal state (Bas), 12 (GH12h) and 36 (GH36h) h after th e last of seven injections of rhGH (3.3 mu g/kg), given at bedtime on alter nate days. In study B, the same parameters were determined in the basal sta te (Bas), 60 (GH60h) and 84 (GH84h) h after the last of seven injections of rhGH (3.3 mu g/kg), given at bedtime at 3 day intervals. MEASUREMENTS The rates of protein metabolism were estimated by infusing [1- C-13]leucine, and those of lipolysis by infusing [1,1,2,3,3-D-5]glycerol. RESULTS Leucine oxidation decreased (P < 0.01) by approximately 30% after G H12h and GH36h but did not change after GH60h and GH84h. Non-oxidative leuc ine disposal increased after GH12h and GH36h by approximately 13% (P < 0.05 ) whereas it did not change after GH60h and GH84h. Glycerol appearance incr eased (P < 0.01) by approximately 45% after GH12h and GH36h but did not cha nge after GH60h and GH84h. CONCLUSIONS The effects on protein and lipid metabolism following the injec tion of rhGH last longer than 36 and less than 60 h. In fact, rhGH administ ration on alternate days induced a sustained increase in the rates of prote in synthesis and lipolysis of GHD adults, whereas a longer interval of admi nistration (3 days) had no effect by 60 h.