[Show abstract][Hide abstract] ABSTRACT: To determine if replacement of GH improves BMD in adult-onset GHD, we administered GH in physiologic amounts to men and women with GHD. GH replacement significantly increased spine BMD in the men by 3.8%.
Growth hormone (GH) deficiency (GHD) acquired in adulthood results in diminished BMD; the evidence that replacement of GH improves BMD is not conclusive. We therefore performed a randomized, placebo-controlled trial to determine whether GH replacement would increase lumbar spine BMD in a combined group of men and women with adult-onset GHD.
We randomized 67 men and women to receive GH (n=33) or placebo (n=34) for 2 yr. The GH dose was initially 2 microg/kg body weight/d, increased gradually to a maximum of 12 microg/kg/d and adjusted to maintain a normal IGF-I concentration for age and sex. BMD was assessed before treatment and at 6, 12, 18, and 24 mo of treatment. Fifty-four subjects completed the protocol.
BMD of the lumbar spine in the entire group increased by 2.9 +/- 3.9% above baseline in the GH-treated subjects, which was significantly (p=0.037) greater than the 1.4 +/- 4.5% increase in the placebo-treated subjects. In a secondary analysis, spine BMD in GH-treated men increased 3.8 +/- 4.3% above baseline, which was significantly (p=0.001) greater than that in placebo-treated men (0.4 +/- 4.7%), but the change in GH-treated women was not significantly different from that in placebo-treated women. Treatment with GH did not increase total hip BMD more than placebo treatment after 2 yr.
We conclude that GH replacement in men who have adult-onset GHD improves their spine BMD, but we cannot draw any conclusions about the effect of GH replacement on spine BMD in women with adult-onset GHD.
Full-text · Article · Jun 2007 · Journal of Bone and Mineral Research
[Show abstract][Hide abstract] ABSTRACT: Although serum insulin-like growth factor I (IGF-I) concentrations have utility as a screening test for growth hormone (GH) deficiency in children and young adults, they are less accurate for screening in adults over 40 years of age. There are two main limitations in the clinical use of IGF-I levels as a marker of GH secretion. First, IGF-I synthesis is not only regulated by GH but also by nutrient supply and by other hormones; second, low IGF-I levels in the presence of normal or increased GH secretion may reflect a peripheral resistance to GH action. Although serum IGF-I cannot be used as a stand-alone test for the diagnosis of adult GH deficiency, very low IGF-I levels in the context of documented hypothalamic or pituitary disease may be helpful in identifying patients with a high probability of GH deficiency. In the presence of two or more additional pituitary hormone deficiencies, an IGF-I level <84 microg/l (assayed by Esoterix Endocrinology, Inc. Calabasas Hills, CA, USA) indicates a 99% probability of GH deficiency. As this cut-off value has not been validated for other IGF-I assays, an IGF-I standard deviation score (SDS) of <-3 may be considered in adults over age 28; an even lower IGF-I SDS is needed for diagnosis in younger adults. In clinical practice, other causes of low serum IGF-I such as malnutrition, diabetes, hypothyroidism, liver disease, etc., should be excluded before applying these diagnostic criteria.