CONTINUOUS SUBCUTANEOUS INFUSION OF LOW-DOSE GROWTH-HORMONE DECREASESSERUM SEX-HORMONE BINDING GLOBULIN AND TESTOSTERONE CONCENTRATIONS INMODERATELY OBESE MIDDLE-AGED MEN

OBJECTIVE Sex-hormone binding globulin (SHBG) is a liver derived prote in whose concentration has been shown to be affected by a number of fa ctors. The aim of the present study was to investigate the possible ef fect of increased basal GH concentrations on serum concentrations of S HBG, testosterone and thyroid hormones. DESIGNS Recombinant human grow th hormone (rhGH) was given as a continuous subcutaneous infusion in a low dose (0.02 U/kg/day) over a period of 14 days in an open study. P ATIENTS Eight middle-aged (42-59 years) overweight (body mass index 26 .1-33.8 kg/m(2)) but otherwise healthy men were studied. MEASUREMENTS Blood samples were obtained after an over-night fast before and after 2, 7 and 14 days of treatment. Serum was separated and stored at -20 d egrees C until assay. RESULTS Serum GH concentrations increased to a s teady level of 2-4 mU/l. Serum SHBG concentration decreased between 2 and 7 days of treatment and serum testosterone concentration changed i n parallel. There was no change in the ratio between serum SHBG and se rum testosterone. Serum T4 and free T4 concentrations decreased, and t hat of T3 increased as a result of continuous GH infusion. Simple corr elations between changes in SHBG concentrations and other hormonal cha nges showed positive significant correlations between changes of SHBG and of testosterone. CONCLUSIONS Low dose continuously infused GH resu lted in a parallel decrease in serum SHBG and testosterone concentrati ons. Thyroid hormone concentrations were affected in a similar way to that previously demonstrated following daily injections of GH.