Effect of Growth Hormone on Lipoprotein Metabolism in Male Pituitary Dwarfs: Changes in Lipoprotein Lipase Activity and Cholesterol Level in HDL Subfractions

To determine the effect of a chronic therapeutic dose (0.24 IU/kg/week) of growth hormone on the cholesterol concentration in serum lipoproteins and postheparin plasma lipase activities in previously untreated children with idiopathic growth hormone deficiency, seven male patients under 10 years of age were studied before and three months after the initiation of growth hormone therapy. Lipase activity was measured by an immunochemical method. The cholesterol concentration in high-density lipoprotein subfractions was determined, using a micromethod for ultracentrifugation. Serum total cholesterol and triglyceride levels did not change significantly during treatment, while the high-density lipoprotein cholesterol level decreased significantly after treatment to 79% of the baseline level, with an equal decrease of cholesterol concentration in both high-density lipoprotein₂ and ₃. Lipoprotein lipase, but not hepatic triglyceride lipase, activity decreased significantly after treatment. These were not associated with changes in either thyroid status as determined by serum triiodothyronine levels or insulin responsiveness after oral glucose challenge, suggesting that these changes may be induced by a direct action of growth hormone.