Endocrine Abstracts

Background. Abnormal lipoprotein composition associated with growth hormone deficiency (GHD) may contribute to increased mortality observed in conventionally replaced hypopituitarism. Aim. To examine the effects of forty weeks of growth hormone replacement (GHR) on lipoprotein composition and LDL size in sixteen GHD hypopituitary subjects. In eight patients, VLDL and LDL composition were additionally assessed after eight weeks. Methods. VLDL and LDL were separated by differential ultracentrifugation. HDL was separated using the dextran sulphate method. ApoB, triglyceride, phospholipid, free and total cholesterol concentrations were measured using an autoanalyser. LDL size was determined following polyacrylamide gel electrophoresis. Results. GHR for 8 weeks induced borderline reductions in VLDL cholesterol ester (0.23(0.16-0.35) to 0.22(0.12-0.37) mg/dl, p=0.06), VLDL apoB (4.83(3.81-7.84) to 4.28(3.36-5.88) mg/dl, p=0.09) and LDL free cholesterol (0.74(0.51-1.05) to 0.58(0.37-0.72) mg/dlp=0.09) levels. Forty weeks of GHR significant increased HDL free cholesterol (0.20(0.17-0.27) to 0.24(0.22-0.25) mg/dl, p=0.03), HDL total cholesterol (1.02(0.87-1.22) to 1.13(1.05-1.35) mg/dl, p=0.01) and HDL cholesterol ester (0.82(0.71-0.95) to 0.88(0.83-1.12) mg/dl, p=0.005) levels. LDL size remained similar (26.63±0.18 to 26.58±0.15 nm, p=0.81) and correlated with VLDL composition (triglyceride, R= -0.67; free cholesterol, R= -0.72; phospholipid, R= -0.72), but not VLDL apoB concentration (R=0.36). Thus, VLDL composition, and not particle concentration, determines LDL size. Conclusion. GHR exerts beneficial anti-atherogenic effects on VLDL and LDL composition. LDL particle size was unaltered.