THE INDIVIDUAL RESPONSIVENESS TO GROWTH-HORMONE (GH) TREATMENT IN GH-DEFICIENT ADULTS IS DEPENDENT ON THE LEVEL OF GH-BINDING PROTEIN, BODY-MASS INDEX, AGE, AND GENDER

The aim of the present trial was to study the individual responsivenes s to GH treatment in terms of body composition and to search for possi ble predictors of the response in GH-deficient adults. Sixty-eight pat ients (44 men and 24 women) with a mean age of 44.3 (1.2) yr and verif ied GH deficiency participated in a 2-phase treatment trial with an in itial randomized, double blind, placebo-controlled, 6-month period, fo llowed by an open treatment period, thereby ensuring all patients 12 m onths of GH treatment. Recombinant human GH was administered sc daily at bedtime, with a target dose of 12 mu g/kg . day. GHBP was measured by ligand-mediated immunofunctional assay, and serum insulin-like grow th factor I(IGF-I) was determined by RIA after acid-ethanol extraction , using a truncated IGF-I analog as the radioligand. Lean body mass (L BM) and body fat (BF) were determined by dual energy x-ray absorptiome try, and total body water (TBW) was determined by bioelectrical impeda nce. During the placebo control period, serum IGF-I, LBM, and TBW incr eased (P < 0.001), whereas BF decreased (P < 0.001) and serum GHBP was unchanged in the group treated with GH compared with the patients tre ated with placebo. After 12 months of GH treatment, the individual cha nges in BF ranged from -12.5 to 4.3 kg and from -4.5 to 10.1 kg in LBM . Age (P < 0.05) and baseline GHBP level (P < 0.01) were inversely cor related with the increase in LBM. The GH-induced increment in IGF-I an d TBW was greater in men than in women (P < 0.01), whereas the decreas es in BF were similar in men and women. This trial demonstrates the va riability in responsiveness to GH administration in GH-deficient adult s. The best response to GH was obtained in younger patients with low G HBP levels. Furthermore, men responded better than women.