(22-09-08) The Effects of Central Adiposity on Growth

<>Hormone Response to GHRH-Arginine Stimulation Testing in Men.

Makimura H, Stanley T, Mun D, You SM, Grinspoon S.
Program in Nutritional Metabolism and Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114.

Context: The relative contribution of central adiposity versus weight on GH response to stimulation testing in obesity is not known. Objective: We aimed to assess the contribution of weight and specific measures of central and peripheral adiposity to GH response to GHRH-arginine testing in lean, overweight and obese men. Design: 75 men (mean age 44.3 +/- 1.1 years old; body mass index (BMI) 28.8 +/- 0.7 kg/m(2)) were investigated. Subjects were classified as lean (BMI < 25 kg/m(2), n = 23), overweight (BMI >/= 25 and < 30 kg/m(2), n = 28) and obese (BMI >/= 30 kg/m(2), n = 24). Subjects were also stratified by waist circumference (WC) (< 102 cm, n = 47; >/= 102 cm, n = 28). Body composition and regional adiposity were assessed by anthropometrics, dual-energy X-ray absorptiometry (DEXA) and abdominal computed tomography (CT) scans. Results: Peak stimulated GH was 36.4 +/- 5.4 microg/L, 16.6 +/- 2.9 microg/L, and 7.6 +/- 0.9 microg/L among lean, overweight, and obese subjects, respectively (p < 0.001 for all comparisons). Peak stimulated GH was 26.9 +/- 3.4 microg/L among subjects with WC < 102 cm compared to 7.9 +/- 0.9 microg/L among subjects with WC >/= 102 cm (p < 0.0001). Separate multivariate models using anthropometric, DEXA and CT derived measures of central adiposity demonstrated strong associations between peak stimulated GH and measures of central adiposity including WC, trunk fat by DEXA and visceral adiposity (VAT) by CT, controlling for age, BMI and more general measures of adiposity. WC was independently associated with peak GH response to GHRH-arginine in a model including age, BMI and hip circumference. In this model, BMI was no longer significant, and peak GH was reduced 1.02 microg/L for each 1 cm increase in WC (p = 0.02). Conclusions: GH response to GHRH-arginine testing is reduced in both overweight and obese subjects and negatively associated with indices of central abdominal obesity including WC, trunk fat and VAT. The use of waist circumference, as a surrogate for central adiposity, adds predictive information to the determination of GH response, independent of BMI.

Source: 1: J Clin Endocrinol Metab. 2008 Sep 2.

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