Defect in epinephrine production in children with craniopharyngioma: functional or organic origin?

Despite pituitary hormone replacement, patients with craniopharyngioma often complain of fatigue. They may have deficient control of catecholamine secretion caused by hypothalamic lesion. Another hypothesis is a functional defect in catecholamine production through either glucocorticoid deficiency because high intraadrenal glucocorticoid concentration is necessary for epinephrine synthesis or unrecognized hypoglycemia, which can intrinsically alter epinephrine secretion. We measured catecholamine response to insulin-induced hypoglycemia and orthostasis, and 24-h urinary catecholamine excretion, in 16 children with craniopharyngioma (patients) and 27 sex- and age-matched short children. We also studied the influence of a 4-fold increase in the usual daily dose of hydrocortisone on catecholamine excretion (50 vs. 12 mg/m(2) of body surface area) in the glucocorticoid-deficient patients. Last, we compared 24-h continuous sc glucose in patients and 10 sex- and age-matched healthy children. The results are expressed as medians (25th, 75th). For a similar blood glucose nadir after insulin administration, peak plasma epinephrine in response to hypoglycemia was lower in patients vs. controls [420 (120, 715) vs. 730 (460, 1200) ng/liter, P < 0.01], whereas peak plasma norepinephrine was higher [390 (280, 550) vs. 270 (180, 280) ng/liter, P < 0.05]. Catecholamine response to orthostasis did not differ between groups. Urinary epinephrine was significantly lower in patients (P < 0.001), whereas urinary norepinephrine was similar. The extent of epinephrine deficiency correlated with neither tumor size nor hypothalamic involvement. A 4-fold higher hydrocortisone dose did not correct the defective epinephrine excretion in the glucocorticoid-deficient patients. Last, the 24-h sc glucose values were similar between patients and controls. In conclusion, children with craniopharyngioma have a defect in epinephrine but not norepinephrine production. There is no proof of a univocal origin, either organic or functional. Whether abnormal catecholamine secretion alters glucose level during fasting or acute illness, or hampers adaptation to exercise, requires further studies.