Very-low-density lipoprotein apolipoprotein B100 kinetics in adult hypopituitarism

Hypopituitarism is associated with hyperlipidemia, the mechanisms of which are not fully known. One possible mechanism is an increased hepatic secreti on of very-low-density lipoprotein (VLDL) apolipoprotein B100 (apo B100). T o investigate this, 13 hypopituitary patients (seven women and six men; age , 46 +/- 3 years [mean +/- SEM]; body mass index [BMI], 29 +/- 2 kg/m(2)) a nd 13 matched controls (seven women and six men; age, 43 +/- 3 years; BMI, 28 +/- 2 kg/m(2)) were investigated in a stable-isotope study. [1-C-13]leuc ine (1 mg/kg body weight) was administered, followed by a continuous B-hour infusion of [1-C-13]leucine (at a rate of 1 mg/kg/h), Patients had a simil ar fractional secretion rate (FSR) of VLDL apo B100 versus controls (0.37 /- 0.05 v 0.38 +/- 0.06 pools/h, respectively), but they had a significantl y larger pool size (3.4 +/- 0.3 v 1.9 +/- 0.3 mg/kg) and higher absolute se cretion rate ([ASR] 27.8 +/- 2.9 v 16.0 +/- 2.5 mg/kg/d). The increase in h epatic VLDL production may explain the lipid abnormalities found in hypopit uitarism. Pasting circulating nonesterified fatty acids (NEFAs) were decrea sed in the patients (284 +/- 26 v 664 +/- 92 mu mol/L, P < .001) despite th e increase in VLDL secretion. An inverse relationship was observed between the NEFA level and VLDL apo B100 FSR in the patients (r(s) = -.85, P < .005 ). Copyright (C) 1999 by W.B. Saunders Company.