LOW-DENSITY-LIPOPROTEIN PARTICLE-SIZE IN HYPOPITUITARY ADULTS RECEIVING CONVENTIONAL HORMONE REPLACEMENT THERAPY

Adults receiving conventional replacement therapy for hypopituitarism are known to have increased cardiovascular mortality. The aim of this study was to assess the lipid profiles of 30 hypopituitary adults comp ared with 2 case control groups, 1 matched for age, sex, and body mass index (BMI) and the second matched for age and sex only with a BMI re presentative of the general population. Fasting lipids, lipoproteins, and apoproteins (Ape) were determined by routine methods. Low density lipoprotein (LDL) particle size was determined by nondenaturing gradie nt gel electrophoresis. LDL size was significantly smaller in the hypo pituitary group (25.9 +/- 0.1 nm) than in the BMI-matched (26.2 +/- 0. 1 nm; P < 0.05) and standard control (26.3 +/- 0.1 nm; P < 0.01) group s. High density lipoprotein cholesterol levels in the hypopituitary gr oup were significantly lower than those in the BMI-matched control gro up (1.13 +/- 0.06 vs. 1.34 +/- 0.06 mmol/L; P < 0.05) and the standard control group (1.38 +/- 0.06 mmol/L; P < 0.005). Apo A1 levels were a lso lower compared with those in the BMI-matched (122 +/- 6 vs. 137 +/ - 4 mg/dL; P < 0.05) and the standard (143 +/- 4 mg/dL; P < 0.005) con trol groups. There was a trend toward higher triglyceride levels when the hypopituitary subjects were compared with the standard control gro up [1.4 (95% CI, 1.3-2.2) vs. 1.0 (95% CI, 0.9-1.4) mmol/L; P = 0.06]. These differences were more marked in the female subjects studied. No significant differences were noted in total cholesterol, LDL choleste rol, or Apo B levels. We conclude that hypopituitary patients receivin g conventional replacement therapy have an atherogenic lipid profile c haracterized by small dense LDL, decreased high density lipoprotein ch olesterol, and increased triglyceride levels, which may contribute to the excess cardiovascular mortality in this group.