The pituitary regulates the body's endocrine system, including the thyroid gland, adrenal cortex, ovaries and testes, through the release of numerous hormones. Pituitary function, in turn, is regulated through complex feedback loops involving the hypothalamus and the target endocrine glands. Hypopituitarism may result from multiple causes, including primary and metastatic cancer, ischemic and granulomatous disease, infection, developmental abnormalities and trauma, which may affect the gland itself (primary hypopituitarism) or the hypothalamus (secondary hypopituitarism). Depending on the anatomic lesion, patients with hypopituitarism may present with signs or symptoms of multiple endocrine abnormalities, such as hypothyroidism, adrenal insufficiency, diabetes insipidus, hypoglycemia, sexual dysfunction and growth retardation. A thorough clinical history, detailed examination, laboratory evaluation of endocrine function and radiographic views of the pituitary and sella turcica can suggest the diagnosis and etiology. Treatment, usually lifelong, may include hormone replacement and medical or surgical correction of the underlying disease.