Assessment of Growth Hormone Dynamics in Human Immunodeficiency Virus-Related Lipodystrophy1

Abstract

Human immunodeficiency virus (HIV) lipodystrophy (LIPO) is characterized by increased visceral adiposity, peripheral fat atrophy, dyslipidemia, and insulin resistance. GH concentrations are known to vary inversely with excess weight and body fat but have not been investigated in HIV lipodystrophy. Twenty-one subjects with HIV LIPO, 20 HIV-infected nonlipodystrophy subjects (NONLIPO), and 20 control (C) subjects were prospectively recruited for this study and compared. Subjects in the three groups were all male, age-matched [median, 47 yr old (interquartile range, 37–50) LIPO; 41 (37–44) NONLIPO; and 43 (37–49) C], and body mass index-matched [median, 24.3 kg/m2 (interquartile range, 22.2–26.6) LIPO; 24.4 (23.3–25.9) NONLIPO; and 24.8 (22.7–26.1) C] (P> 0.05 for all comparisons). Visceral abdominal fat [16,124 mm2 (11,246–19,790) LIPO; 7,559 (5,134–11,201) NONLIPO; and 8,803 (6,165–11,623) C; P < 0.01 LIPO vs. NONLIPO and LIPO vs. C] and the ratio of visceral abdominal fat to sc abdominal fat [1.37 (0.71–2.44) LIPO vs. 0.57 (0.47–0.78) NONLIPO vs. 0.55 (0.41–0.71) C, P < 0.01 LIPO vs. NONLIPO and LIPO vs. C] were significantly increased in the LIPO subjects but were not significantly different between NONLIPO and C. The mean overnight GH concentration, determined from frequent sampling every 20 min (from 2000 h to 0800 h) was decreased in the LIPO subjects [0.38 μg/L (0.13–0.67) LIPO vs. 0.96 (0.53–1.30) NONLIPO vs. 0.81 (0.49–1.03) C, P < 0.05 LIPO vs. NONLIPO and LIPO vs. C] and not significantly different between NONLIPO and C. Pulse analysis demonstrated decreased baseline GH [0.08 μg/L (0.06–0.21) LIPO vs. 0.19 (0.10–0.32) NONLIPO vs. 0.17 (0.12–0.57) C, P < 0.05 LIPO vs. NONLIPO and LIPO vs. C] and GH peak amplitude [1.06μ g/L (0.46–1.94) LIPO vs. 2.47 (1.22–3.43) NONLIPO and 2.27 (1.36–4.25) C, P < 0.05 LIPO vs. NONLIPO and LIPO vs. C] in the LIPO subjects but no significant difference in pulse frequency. No significant differences were observed between NONLIPO and C for any GH parameter. Insulin-like growth factor-I was not different between the groups. Total body fat (r = −0.40, P = 0.01) and visceral fat (r = −0.58, P = 0.0001) correlated inversely with mean overnight GH concentrations in the HIV-infected patients. In a multivariate regression model, controlling for age, body mass index, body fat, and visceral fat, only visceral fat was a significant predictor of mean GH concentrations (P = 0.0036, r2 for model = 0.40). These data demonstrate normal GH pulse frequency and insulin-like growth factor-I concentrations but reduced mean GH concentrations, basal GH concentrations, and GH pulse amplitude in patients with HIV lipodystrophy. Increased visceral adiposity is the strongest predictor of reduced GH concentrations in HIV lipodystrophy. Further studies are necessary to determine the clinical significance of reduced GH in patients with HIV lipodystrophy.