The Effects of Growth Hormone on Carbohydrate and Lipid Metabolism

Hwang, Heeyu; Chung, So Chung; Kim, Duk Hi

Abstract

PURPOSE
Growth hormone stimulates longitudinal growth, and it also exerts various effects on the metabolism of carbohydrates, lipids and proteins, indirectly regulating fuel metabolism. A hallmark is the stimulation of lipolysis, suppression of glucose oxidation, and development of insulin resistance. These metabolic effects subsequently affect body composition and atherogenic risk factors. There have recently been numerous reports concerning the metabolic effects of growth hormone, but the results are conflicting and exact cellular mechanism of action is yet unknown. The aim of this study is to assess the effect of biosythetic growth hormone replacement on carbohydrate and lipid metabolism and its subsequent effect on atherogenic risk in growth hormone deficient and idiopathic short stature.
METHODS
We studied 111 idiopathic short stature patients and 12 children diagnosed with growth hormone deficiency by growth hormone provocation tests. Subjects were divided into three groups on the basis of duration of treatment; those who had been receiving GH replacement for 6, 12 and 18 months. Growth hormone was adminstered in a subcutaneous dose of 0.1 units per kg 6 times a week, and levels of blood sugar, total cholesterol, triglycerides, HDL-cholesterol, free fatty acid were measured before and after treatment in each group and changes in the atherogenic index (calculated as total cholesterol/HDL-cholesterol) were compared.
RESULTS
1)Blood sugar levels showed no significant change after GH therapy in both idiopathic short stature and growth hormone deficient groups. 2)Levels of total cholesterol showed a signficant decrease 6, 12 and 18 months after GH therapy in the idiopathic short stature patients, but no signficant change was noted in the growth hormone deficient patients. 3)GrowthhormonetherapyshowednosignificanteffectoneitherHDL-cholesterol or atherogenic index in both idiopathic short stature and growth-hormone deficient children. 4)There was no significant change in triglyceride and free fatty levels in children with idiopathic short stature after growth hormone therapy.
CONCLUSIONS
Growth hormone administration significantly lowered total cholesterol levels in idiopathic short stature children, but failed to have a significant effect on atherogenic risk. Despite the increasingly widespread use of growth hormone in the treatment of hypopituitarism and non-GHD short stature, data concerning the metabolic effects of growth hormone are conflicting and the precise underlying mechanism is yet to be revealed, making further research necessary to determine the long term consequences of growth hormone replacement.