Adrenal and thyroid function in the fetus and preterm infant.

[congenital adrenal hyperplasia]

Adrenal and thyroid hormones are essential for the regulation of intrauterine homeostasis , and for the timely differentiation and maturation of fetal organs . These hormones play complex roles during fetal life , and are believed to underlie the cellular communication that coordinates maternal -fetal interactions . They serve to modulate the functional adaptation for extrauterine life during the perinatal period . The pathophysiology of systemic vasopressor-resistant hypotension is associated with low levels of circulating cortisol , a result of immaturity of hypothalamic -pituitary -adrenal axis in preterm infants under stress . Over the past few decades , studies in preterm infants have shown abnormal clinical findings that suggest adrenal or thyroid dysfunction , yet the criteria used to diagnose adrenal insufficiency in preterm infants continue to be arbitrary . In addition , although hypothyroidism is frequently observed in extremely low gestational age infants , the benefits of thyroid hormone replacement therapy remain controversial . Screening methods for congenital hypothyroidism or congenital adrenal hyperplasia in the preterm neonate are inconclusive . Thus , further understanding of fetal and perinatal adrenal and thyroid function will provide an insight into the management of adrenal and thyroid function in the preterm infant .