hypopituitism

Hypopituitarism, commonly spelled hypopituitarism but sometimes referred to as hypopituitism, is a disorder in which the pituitary gland fails to secrete adequate amounts of one or more pituitary hormones. It may affect a single hormonal axis (partial hypopituitarism) or several axes (panhypopituitarism). Because the pituitary regulates other endocrine glands, the resulting hormone deficiencies are described as central or secondary hypopituitarism. Involvement of the posterior pituitary can cause diabetes insipidus, a separate axis of dysfunction.

Common causes include pituitary adenomas and their treatment (surgery or radiotherapy), postpartum pituitary infarction (Sheehan syndrome), head trauma, cranial irradiation, infiltrative or inflammatory diseases (such as sarcoidosis or hemochromatosis), infections, vascular events, and genetic or developmental disorders. In many cases the exact cause remains unidentified.

Deficiencies of anterior pituitary hormones produce a range of symptoms. ACTH deficiency leads to secondary adrenal insufficiency with fatigue, weakness, hypotension, nausea, and hypoglycemia. TSH deficiency causes secondary hypothyroidism with fatigue and weight gain. LH/FSH deficiency results in hypogonadism, causing reduced libido, infertility, or menstrual irregularities. GH deficiency causes short stature in children and reduced muscle mass or quality of life in adults. Posterior pituitary involvement leads to diabetes insipidus, presenting as excessive urination and thirst. Acute pituitary failure is a medical emergency if the stress response is impaired.

Diagnosis relies on clinical suspicion, hormonal testing showing multiple low pituitary axes, and MRI to identify pituitary or hypothalamic pathology. Management focuses on treating the underlying cause and replacing deficient hormones: glucocorticoids for ACTH deficiency, thyroid hormone for TSH deficiency (after glucocorticoids), sex hormones as indicated, growth hormone in selected patients, and desmopressin for diabetes insipidus. Regular follow-up is essential.