Impact of 5 years of growth hormone replacement therapy on cardiovascular risk factors in growth hormone–deficient adults

Abstract

The benefits of long-term effects of growth hormone (GH) substitution on carbohydrate and lipid metabolism in GH-deficient (GHD) adults are still controversial. The purpose of this study was to evaluate the effects of 5 years of GH substitution on body composition, glucose and lipid metabolism, and carotid artery intima-media thickness (IMT) in GHD adults. Fourteen patients were clinically assessed every 3 months for 5 years. Serum insulin-like growth factor 1 levels, lipid profile, oral glucose tolerance test, and ultrasonography of the carotid arteries were performed at baseline, 6 months, and every year during replacement. Visceral fat was measured by computed tomographic scan at baseline and at 6, 12, 24, and 60 months. The waist circumference was reduced after 6 months but increased during the next months toward baseline values. Visceral fat decreased during the study. Fasting glucose and insulin levels did not change, as well as the homeostasis model assessment of insulin resistance index. Despite an initial increase in frequency of abnormal glucose tolerance, mean 2-hour oral glucose tolerance test glucose levels decreased during the last 2 years. There was an increase in apolipoprotein A-1 levels during the treatment. Apolipoprotein B levels were reduced after 6 months and remained stable thereafter. A reduction in carotid artery IMT was observed during replacement. We concluded that 5 years of GH replacement therapy promoted positive effects on visceral fat, lipid profile, and carotid artery IMT in GHD adults. Long-term therapy improves insulin sensitivity through a reduction in visceral fat, and continuing monitoring is mandatory in terms of glucose metabolism.