Serum lipid and leptin concentrations in hypopituitary patients with growth hormone deficiency

OBJECTIVE: To investigate the effects of growth hormone (GH) deficiency on serum lipid and leptin concentrations in hypopituitary patients taking conv entional replacement therapy and to determine the relations between leptin and gender and anthropometric and metabolic variables. SUBJECTS: Twenty-one GH deficient adult hypopituitary patients (15 women, s ix men) and 21 (14 women, seven men) age, sex and body mass index (BMI) mat ched healthy controls. MEASUREMENTS: After an overnight fast, anthropometric parameters were measu red and body composition was determined by a bioelectrical impedance analys er. Venous blood samples were obtained for the measurements of glucose, tot al cholesterol, high density lipoprotein (HDL) cholesterol, triglyceride, i ntact insulin, insulin-like growth factor 1 (IGF-1) and leptin concentratio ns. Serum leptin and hormones were analysed by radioimmunoassay. RESULTS: Hypopituitary patients with On deficiency showed significantly hig her triglyceride, total and low density lipoprotein (LDL) cholesterol and l ower HDL cholesterol concentrations on conventional replacement therapy. Th e unfavourable lipid profile was particularly evident in women. Significant ly higher leptin concentrations were found in patients compared with health y controls with similar body fat content (23.5 +/- 11.8 ng/ml vs 11.7 +/- 6 .9 ng/ml, P = 0.01). This difference remained significant even when leptin values were expressed in relation to fat mass percentage (0.79 +/- 0.40 vs 0.42 +/- 0.17 ng/ml%, P < 0.05) and fat mass kg (1.32 +/- 0.81 vs 0.66 +/- 0.30 ng/ml kg, P < 0.05). Significant positive correlations were observed b etween leptin concentrations and body fat percentage and age in the control group. In patients the sole significant relation between leptin and study parameters was the positive correlation observed between leptin and total c holesterol concentrations. Serum leptin concentrations were significantly h igher in women than men in the control group, but not in the patients. No s ignificant gender difference was observed when leptin concentrations were e xpressed in relation to fat mass (percentage and kg). CONCLUSION: Growth hormone deficient hypopituitary patients (particularly w omen) on conventional replacement therapy have a more atherogenic lipid pro file. Leptin concentrations are increased in GH deficient adults even after adjustment for percentage body fat and body fat mass (kg). Although the na ture of our data does not allow us to draw any conclusions on the mechanism (s) of increased leptin concentrations in GH deficiency, decreased central sensitivity to leptin and increased leptin production from per unit fat mas s, or alterations in leptin clearance, might be operative.