Endocrine function in four anencephalic infants.

Endocrine studies of 4 anencephalic infants were carried out. No hypothalamic or hypophyseal structures could be found in any of them macroscopically, but we cannot say that there were no functioning pituitary cells which might have been seen microscopically. A combined LH-RH and TRH test was performed in the 6th h of life, followed by an intravenous glucose tolerance test 1 h later. Our data suggest that: (1) adenohypophyseal tissue, present in anencephaly even in the absence of a hypothalamus, is able to synthesize PRL and TSH autonomously and, under specific stimulation, PRL, TSH, and ACTH can be released while FSH and LH-HCG are not, hGH secretion is doubtful; (2) the circulating hGH and TSH surges that normally occur after delivery are hypothalamus-dependent and do not occur in anencephalics; (3) the thyroid and adrenals are able to synthesize hormones when specifically stimulated, even in the absence of the hypothalamus, and (4) beta-pancreatic function is not markedly impaired in anencephaly.