Hypopituitarism and Growth Hormone Deficiency

Hypopituitarism, which was first described by Simmonds in 1914, refers to the deficiency of one or more pituitary hormones.1 It arises because of a defect in hormone pro-duction within the pituitary gland itself or when there is an insufficient supply of hypothalamic-releasing hor-mones. Hypopituitarism is commonly seen in endocrine practice and, despite treatment of hormone deficiency syndromes, is associated with increased morbidity and mortality. Clinical manifestations are influenced by the underlying cause, type, severity, and rate of onset of pitu-itary hormone deficiency.Adult patients with hypopituitarism receive substitu-tive hormone treatment for secondary glucocorticoid, thyroid hormone, sex steroid, and antidiuretic hormone (ADH) deficiency. Historically, growth hormone (GH) deficiency was not regarded as clinically important in adults as it was assumed that GH had no physiologic rel-evance after cessation of childhood growth. The advent of genetic engineering resulting in abundant supplies of recombinant GH has led to a major reappraisal of its physiologic role in adult life. GH continues to be pro-duced throughout adult life and is the most abundant hormone in the adult pituitary gland. Many countries have approved the use of GH for replacement therapy in adults with GH deficiency.