Increased leptin and tumour necrosis factor α per unit fat mass in hypopituitary women without growth hormone treatment

Abstract

Background: The adipocyte products, leptin and tumour necrosis factor (TNF)α, are associated with atherosclerotic diseases and may be factors contributing to the enhanced cardiovascular risk in hypopituitary patients with growth hormone (GH) deficiency. Objective: To investigate whether leptin and TNFα are increased in a group of hypopituitary women previously found to have increased cardiovascular morbidity, and to compare them with matched individuals of the same sex and age and with similar body composition. Design and Patients: Thirty-three GH-deficient women with a median age of 64 years (range 39-77 years) were investigated cross-sectionally. The patients were compared with 33 controls matched for sex, age, smoking habits, educational level and residence. Methods: Body composition was measured by bioimpedance analysis. Fasting concentrations of leptin, TNFα and insulin were analysed in patients and controls. Results: There was no significant difference in body mass index or fat mass between patients and controls (both P≥0.4). Serum leptin did not differ significantly between patients and controls. However, when serum leptin concentrations were expressed per kilogram fat mass, the patients had significantly greater concentrations (P = 0.01). Serum TNFα and TNFα per kilogram fat mass were also significantly greater in the patients (both P = 0.001). In contrast, serum insulin did not differ significantly between patients and controls. In the patients, serum leptin concentrations correlated positively with kilogram fat mass (r = 0.54, P = 0.002). Leptin concentration per kilogram fat mass was positively correlated with insulin (r = 0.40, P = 0.03). Conclusions: In contrast to serum concentrations of TNFα, serum leptin did not differ from that in controls, implying that leptin is not a major contributor to the previously found increase in cardiovascular morbidity in the hypopituitary women investigated. However, the patients had increased leptin concentrations per unit fat mass, indicating an altered adipocyte secretory function in this group.