Hypopituitarism

The pituitary coordinates several endocrine glands. When pituitary tissue or its hypothalamic connection is damaged, the downstream glands may be structurally normal but receive too little stimulation. The result is hypopituitarism: partial or complete deficiency of one or more anterior pituitary hormones, sometimes accompanied by posterior pituitary dysfunction. The clinical danger depends less on the word hypopituitarism than on the missing hormone axis. - ACTH deficiency reduces cortisol production and can cause secondary adrenal insufficiency. - TSH deficiency reduces thyroid hormone production and causes central hypothyroidism. - LH and FSH deficiency impair ovarian or testicular hormone production and fertility. - Growth hormone deficiency affects body composition, exercise capacity, bone health, and metabolic function in adults. - ADH deficiency, when the posterior pituitary or stalk is involved, causes central diabetes insipidus with inability to conserve water. Pituitary macroadenomas are a common acquired cause. Other causes include pituitary surgery or radiation, traumatic brain injury, pituitary apoplexy, severe postpartum haemorrhage causing pituitary infarction, hypophysitis, infiltrative disease, congenital disorders, and hypothalamic lesions. A useful clinical pattern is that several “target-gland” hormones are low at...