Alterations in the concentration of cholesterol in bile after administration of human growth hormone.

Abstract

Extract: To determine the influence of human growth hormone (hGH) on gall bladder bile composition, bile (concentration and molar percentage of cholesterol, bile acids, and phospholipids) was examined in three growth hormone-deficient patients and in one control subject with constitutional short statute, but with adequate secretion of growth hormone. Investigations were made before and after 0.3, 4, and 12 months of therapy with exogenous hGH, 3 U/week. Two patients responded to hGH with accelerated growth (increase in height velocity from 1.3 and 0.2 cm/year to 10.5 and 3.0 cm/year, respectively), but, during the same time, the cholesterol concentration in bile increased progressively, raising the “lithogenic index” from 1.00 and 0.93 to 1.66 and 1.10, respectively. Normally, the “lithogenic index” is 1.00 or less. The third patient also showed some growth acceleration, but his bile did not become oversaturated with cholesterol. The bile of the control subject was excessively saturated with cholesterol after 0.3 months of treatment with hGH, raising the “lithogenic index” from 0.10 to 2.94, the highest yet reported in man. However, this abnormal response to hGH was not sustained, and bile composition returned to normal later on. The data obtained in this study suggest, but do not prove, that hGH might influence cholesterol secretion into bile. Speculation: Normally, biliary cholesterol is kept in micellar solution by bile acids and phospholipids. An increase in the concentration of cholesterol in bile, without a concomitant increase of bile acids and/or phospholipids, causes oversaturation of bile with cholesterol, as expressed in changes of the lithogenic index. The lithogenic index is a quantitative expression of the cholesterol saturation in bile by a single figure which represents all three major biliary lipids. Oversaturation of bile with cholesterol is now recognized as a probable prerequisite for the formation of cholesterol gall stones. Further studies should now define the influence of hGH on biliary cholesterol secretion rates.