Effect of short-term recombinant growth hormone administration on plasma lipoproteins in elderly adults

To characterize the effects of recombinant human growth hormone (rhGH) on plasma lipids and lipoproteins, rhGH was administered daily at a dose of 40 micrograms.kg-1 (Genentech) for 14 days in 7 healthy elderly male (67.4 +/- 1.9 years, 75.8 +/- 2.6 kg) adults. Six other healthy males (63.9 +/- 0.7 years, 77.8 +/- 3.8 kg) served as concurrent controls. Total plasma cholesterol (TC), triglycerides (TG), very-low-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, very-low-density lipoprotein-TG (VLDL-TG) and apolipoprotein AI and apolipoprotein B were determined after an overnight fast before and after the 14-day period of rhGH administration. Subcutaneous rhGH administration was physiologically effective, as shown by a threefold increase in insulin-like growth factor-I (from 110.8 +/- 8.2 to 355.5 +/- 41.6 ng.ml-1; p < 0.05). Plasma fasting insulin also increased from 38.0 +/- 6.5 to 129.9 +/- 43.8 mumol.l-1 (p < 0.05) at the end of the 14 days of rhGH treatment. With respect to plasma lipid/lipoprotein changes, rhGH administration increased plasma TG levels (from 1.5 +/- 0.3 to 2.2 +/- 0.4 mmol.l-1; p < 0.05) and VLDL-TG (from 1.1 +/- 0.3 to 1.8 +/- 0.4 mmol.l-1; p < 0.05), but did not change TC (from 5.0 +/- 0.4 to 5.2 +/- 0.3 mmol.l-1) or any other lipid/lipoprotein variables measured. No significant lipid changes were noted in the control group over the 14-day period. These data suggest that short-term rhGH treatment significantly alters plasma variables of TG profile, perhaps by altering metabolic parameters (i.e. synthesis and/or clearance rates) of VLDL metabolism.