Consultation with the Specialist: Growth Hormone

Abstract

Multiple hormones participate in the endocrine regulation of growth, including thyroid hormone, androgens, and estrogens. Growth hormone (GH), the major hormone involved in postnatal skeletal growth, is a protein having an approximate molecular weight of 21 000 d and produced by the anterior pituitary. Interestingly, GH appears to play little part in fetal growth. An infant who has congenital GH deficiency typically has a normal birth length and weight. Congenital hypoplasia of the anterior pituitary is suggested more commonly by the presence of neonatal hypoglycemia or microphallus in the male. An abnormal growth pattern in children who have congenital GH deficiency becomes apparent, however, by 3 to 6 months of age. Although congenital GH deficiency results from hypoplasia of the hypothalamus or anterior pituitary, GH deficiency may be the first clinical manifestation of a variety of clinically significant disorders. Central nervous system tumors, most classically craniopharyngiomas and histiocytosis X, may cause GH (and other pituitary) deficiency. Other etiologies include cranial trauma, infiltrative disorders, and cranial irradiation. Sometimes, congenital disorders causing partial GH deficiency may not become apparent until late childhood and will present as if they are acquired disorders. Familial forms of GH deficiency and septo-optic dysplasia (absence of the septum pelucidum, hypoplasia of the optic chiasm, and pituitary insufficiency) are congenital disorders that may become evident clinically beyond the neonatal period.