Failure of Glucose Infusion to Suppress the Exaggerated GH Response to GHRH in Patients with Anorexia Nervosa

The growth hormone (GH) response to GH-releasing hormone (GHRH) is characteristically exaggerated in anorexia nervosa (AN). Hyperglycemia suppresses the GH response to GHRH in normal subjects. To test whether this inhibitory action of hyperglycemia is preserved in AN, we performed a GHRH (GHRH 1–40, 1 μg/kg) test under basal conditions (saline infusion) and during steady-state hyperglycemia (200 mg/dl, induced by the intravenous administration of 8 mg/min.kg of glucose) in 6 adolescent girls with acute-stage AN (as diagnosed by psychopathological, hormonal, and nutritional criteria) and in 5 age-matched female controls. In control subjects, GHRH stimulated GH release during saline, but not glucose, infusion. In the anorectic patients, the GH response to GHRH was exaggerated during both saline infusion (2.97 ± 0.79 versus 0.52 ± 0.22 μg.120 min.ml−1, p < 0.02) and under hyperglygemic conditions (4.61 ± 0.56 versus 0.33 ± 0.10, p < 0.001). We conclude that the inhibitory action of hyperglycemia on GHRH-induced GH release is lost in the acute phase of AN.