Growth hormone treatment in adults with adult-onset growth hormone deficiency increases iliac crest trabecular bone turnover: A 1-year, double-blind,randomized, placebo-controlled study

The effects of growth hormone (GH) substitution on bone metabolism were eva luated by dynamic histomorphometry on iliac crest bone biopsies, Twenty-nin e patients, aged 21-61 years (mean 45.5 years), with adult-onset GH deficie ncy (GHD) were randomized to receive subcutaneous injections with GH (2 IU/ m(2)/day = 0.67 mg/m(2)/day) or placebo for 12 months, Serum insulin-linke growth factor I (IGF-I) levels increased 263 +/- 98% (mean +/- SD) during G H treatment (p < 0,0001), In the GH group, osteoid surface increased during treatment from 11% (3-15%) (median [25-75 percentiles]) to 21% (10-27%) (p = 0.01) and mineralizing surface from 4% (1-8%) to 11% (7-16%) (p = 0,04), Moreover, erosion surface tended to increase in the GH group from 2% (1-3% ) to 4% (3-5%) (p = 0.07), The quiescent surface decreased in the GH group from 87% (83-96%) to 74% (68-87%) (p = 0,01), The adjusted appositional rat e, mineral apposition rate, bone formation rate, bone erosion rate, mineral ization lag time,and osteoid thickness remained unchanged during treatment, Erosion depth showed a trend toward increase in the GH group (p = 0,09), w hereas wall thickness was unchanged, Bone balance at the remodeling unit le vel and activation frequency were unchanged, At the tissue level, bone eros ion rate increased significantly from 26% (17-36%)/year to 39% (23-72%)/yea r (p = 0,03). Similarly, the bone formation rate at the tissue level tended to increase, from 24% (15-31%)/year to 36% (17%-63%)%/year(p = 0,06), Fina lly, bone balance at the tissue level decreased significantly from 1% (-2-2 %)/year to --5% (-13-1%)/year (p = 0,01), No significant difference in chan ge was seen in the cancellous bone volume, We conclude that 12 months of GH substitution therapy increases trabecular bone turnover, Moreover, our dat a suggest that bone balance at the bone multicellular unit level is not cha nged to positive.