Energy Homeostasis in Hypopituitary Children and Controls

Abstract

27 children aged 4-16 yrs with hypopituitarism were studied before (I) and after 6 months of growth hormone therapy (II) and compared with 15 endocrinologically normal children aged 2-12 yrs (8 short stature & 7 suspected hypoglycemia) (III). Plasma glucose (G), insulin (IRI), glucagon (IRG), free fatty acids (FFA) and β-hydroxybutyrate (BOH) were measured serially during a fast and following intravenous glucagon administration which terminated the fast after a maximum of 24 hrs. The mean G nadir during the fast was 51 mg% in I, 44 mg% in II and 44 mg% in III. The glucagon stimulated G rise was significant (35 mg% in I, 33 mg% in II and 35 mg% in III). The FFA concentrations at 0 time were .59, .57 & .67 meq/1 in I, II and III respectively. In all 3 groups there was a significant increase of FFA to 1.67, 1.70 & 2.06 meq/1 in I, II & III resp. There were no intergroup differences in any of these results. BOH rose equally in groups I & II. There was a significant IRG rise during the fast of 200 pg/ml in I, 197 pg/ml in II & 234 pg/ml in III. Basal IRI values and IRI responses to glucagon were not different in I & II, but significantly higher than III at both times. The higher IRI values in I & II reflect the frequently associated obesity, particularly in older children. We conclude that energy homeostasis in hypopituitarism during fasting is associated with appropriate fat mobilization, ketone production and IRG responses. In 4 patients in I & 2 in III who became hypoglycemic (G<40 mg%) responses were similar.