EVALUATION OF SINGLE ORAL DOSE METYRAPONE TESTS IN CHILDREN WITH HYPOPITUITARISM Comparison with the Prolonged Metyrapone and Insulin Induced Hypoglycaemia Tests and Their Relationship with the Etiology of Hypopituitarism

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Abstract
Pituitary-adrenal reserve was evaluated in control and hypopituitary subjects by comparing the 8 a.m. plasma 11-deoxycorticoid response (11-DOCS) to a single midnight oral dose of methyrapone (short test) with the 8 a.m. 11-DOCS increase under repeated oral doses of metyrapone (prolonged test) and with the plasma corticoid response during the arginine-insulin test. In the short and the prolonged metyrapone tests, the same response was obtained in 25 of 27 patients. The short test was repeated in 22 patients and the 11-DOCS response did not show a significant difference. In 34 of 40 patients, the response to the short test was comparable to the response during the arginine-insulin test; only 3 patients with a normal 11-DOCS rise to the short test had a low response to insulin and vice versa. Among the low responders to the short test, the mean 11-DOCS value was significantly lower in subjects with operated craniopharyngiomas than in idiopathic hypopituitary patients (P < 0.001). In the short test, the 8 a.m. baseline cortisol value was positively correlated with the 8 a.m. 11-DOCS response (P < 0.001); the cortisol level permitted prediction of the 11-DOCS response in 28 of 53 patients. The short oral metyrapone stimulation was a reliable test in hypopituitary children.