Growth hormone (GH) status is an independent determinant of serum levels of cholesterol and triglycerides in healthy adults.

Abstract

Both severe growth hormone (GH) deficiency in hypopituitary adults and physiological ageing are associated with an increase in fat mass, dyslipidaemia, and an increased incidence of cardiovascular disease. Ageing is also associated with a physiological decrease in spontaneous as well as stimulated GH secretion. We wished to evaluate the effects of endogenous GH status on circulating lipoproteins. A cross-sectional study. Forty-two healthy nonobese adults of both sexes (20 M + 22 F) aged 27-59 years. Twenty-four hour GH secretion, arginine-stimulated GH secretion, and fasting values of lipoproteins and triglycerides. Body composition was measured by CT-scan and whole body DXA-scan. VO2-max was measured on an ergometer bicycle. GH secretion decreased with age and was lower in males. Older subjects had more total body fat, subcutaneous abdominal fat, and intra-abdominal fat than younger ones, and their VO2-max was decreased. Men had more intra-abdominal and subcutaneous abdominal fat but less total body fat than women. There was no sex difference in VO2-max. Total cholesterol (TC) and LDL-C (mmol/l) were higher in older than in the younger subjects (TC: 5.32 (95% CI = 0.49) vs. 4. 17 (95% CI = 0.28), P < 0.001; LDL-C: 3.66 (95% CI = 0.52) vs. 2.54 (95% CI = 0.37), P = 0.001) without sex differences. HDL-C did not show any difference with age or between sexes. Triglycerides (mmol/l) were higher in older subjects and in males (older: 1.36 (95% CI = 0.19) vs. younger: 1.02 (95% CI = 0.20), P = 0.015; M: 1. 34 (95% CI = 0.24) vs. F: 1.03 (95% CI = 0.16), P = 0.03). There was no age-difference in lipoprotein (a), but concentrations were higher in women (M: 4.35 (2.95-8.30) vs. F: 19.40 (4.10-32.80), P = 0.03). TC, LDL-C, and triglycerides correlated positively with age and indices of adiposity, and inversely with VO2-max. TC, LDL-C, and triglycerides also correlated significantly and negatively with arginine-stimulated GH secretion (peak GH) (TC vs. peak GH (r = - 0. 395, P = 0.01); LDL-C vs. peak GH (r = - 0.365, P = 0.017); triglycerides vs. peak GH (r = - 0.386, P = 0.01)). Multiple linear regression analysis showed GH status to be an independent predictor of both TC, LDL-C, and triglycerides. We hypothesize that GH may exert direct effects on lipid metabolism.