Growth Hormone Dynamics in AIDS Lipodystrophy

Massachusetts General Hospital, Boston MA

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Abstract

The purpose of this protocol is to characterize GH secretory dynamics in HIV-infected patients experiencing fat redistribution (lipodystrophy). Preliminary data suggest that increased adiposity and particularly truncal adiposity resulting from HIV-associated lipodystrophy may be related to reduced growth hormone secretion. For example, data obtained in 40 male eugonadal HIV-infected patients indicate an inverse correlation between fat mass by DEXA and mean overnight GH levels (r=0.32; P=0.046). Additionally, GH stimulation to standard arginine testing correlates inversely with trunk-to-extremity fat ratio in this population (r=0.4; P=0.015). While the causal mechanism of this relationship between adiposity and GH secretion is uncertain, the identification of increased total body and truncal adiposity in non-HIV infected patients with known GH deficiency suggests that relative or absolute GH deficiency in patients with the lipodystrophy syndrome may further relative or absolute GH deficiency in patients with the lipodystrophy syndrome may further contribute to fat redistribution. The clinical relevance of this study relates to the potential utility of GH administration in GH deficient patients with the lipodystrophy syndrome, in whom exogenous GH may reduce truncal adiposity and improve body composition. The protocol utilizes multiple tests of body composition and growth hormone dynamics to investigate the relationship between fat mass, fat distribution, and GH secretion, particularly in patients with HIV-associated lipodystrophy. Sixty patients will participate in the study: 20 HIV-infected males with lipodystrophy, 20 HIV-infected age-matched controls without lipodystrophy, and 20 HIV-negative age-matched normal male controls. Participation requires a screening visit to determine eligibility, a one-night inpatient stay, and a two hour outpatient visit. Potential participants will have a screening visit on the GCRC. After informed consent is obtained, patients will have a medical history interview, a physical exam, a blood draw for CBC, and anthropometric measurements of the neck, midarm, trunk, and hips. Patients will be excluded from the study for any of the following: age <18 or age >60; Hgb <9.0g/dL; history of diabetes mellitus or other severe chronic illness; or use of Megace, antidiabetic agents, GH, testosterone or other anabolic agents, pharmacologic glucocorticoid, or prednisone >5mg/day or its equivalent for 3 months prior to enrollment. HIV-positive patients (lipodystrophic and non-lipodystrophic) must have previously diagnosed HIV infection and a stable antiviral regimen for at least 6 weeks prior to enrollment. For the purposes of the study, a waist-to-hip ratio >9.0 and recent change in body fat distribution (i.e., increased abdominal girth in association with peripheral fat wasting) will be used to define the lipodystrophy syndrome. HIV-positive lipodystrophy patients must have waist-to-hip ratio >9.0 and evidence at least one of the following recent changes: increased abdominal girth, relative loss of fat in the extremities, and/or relative loss of fat in the face. Non-lipodystrophic controls (HIV-infected and HIV-negative) must have no recent evidence of the above changes and must have a waist-to-hip ratio <9.0 and a normal BMI (20 kg/m^2<BMI< 26 kg/m^2).