- Partial or complete deficiency of one or any combination of anterior pituitary hormones.
- Adrenocorticotropic hormone deficiency: reduced adrenal secretion of cortisol, testosterone, and epinephrine; aldosterone secretion remains intact.
- Growth hormone (GH) deficiency: short stature in children; asthenia, obesity, and increased cardiac mortality in adults.
- Prolactin deficiency: inhibition of postpartum lactation.
- Thyroid-stimulating hormone (TSH) deficiency: secondary hypothyroidism.
- Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) deficiency: hypogonadism and infertility in men and women.
Hypopituitarism can be caused by either hypothalamic or pituitary dysfunction. Patients with hypopituitarism may have single or multiple hormonal deficiencies (Table 26–1). When one hormonal deficiency is discovered, others may be present.
Table 26–1. Pituitary
Hypopituitarism with mass lesions
Lesions in the hypothalamus, pituitary stalk, or pituitary can cause hypopituitarism. Pituitary adenomas are usually sporadic but are sometimes part of multiple endocrine neoplasia type 1 (MEN 1). Pituitary tumors that arise in MEN 1 usually secrete prolactin (63%), GH (9%), or both (10%) and are more aggressive than sporadic adenomas. Pituitary tumors rarely cause diabetes insipidus. Other types of mass lesions include granulomas (eg, granulomatosis with polyangiitis [formerly Wegener granulomatosis], tuberculosis, cholesterol granuloma), Rathke cleft cysts, apoplexy, metastatic carcinomas, aneurysms, and brain tumors (craniopharyngioma, meningioma, dysgerminoma, glioma, chondrosarcoma, chordoma of the clivus). Postpartum pituitary necrosis (Sheehan syndrome), and African trypanosomiasis are rare causes. Langerhans cell histiocytosis usually presents in youth with diabetes insipidus or hypopituitarism; osteolytic bone lesions are noted on radiographs.
Lymphocytic hypophysitis is an autoimmune disorder that most typically affects peripartum women. It can cause a pituitary mass that mimics a tumor. It usually results in ACTH deficiency but can cause deficiencies in any pituitary hormone. About 25% of cases are associated with other autoimmune conditions, such as systemic lupus erythematosus. Hypophysitis can also be caused by chemotherapeutic drugs (eg, ipilumimab, monoclonal anti-CTLA4 antibodies that enhance immunity).
Hypopituitarism without mass lesions
Congenital hypopituitarism occurs in syndromes such as septo-optic dysplasia (de Morsier syndrome) and in patients with PROP1 and other gene mutations. Cranial radiation, pituitary surgery, encephalitis, hemochromatosis, autoimmunity or coronary artery bypass grafting (CABG) may also cause hypopituitarism. At least one pituitary hormone deficiency develops in about 25–30% of survivors of moderate to severe traumatic brain injury (Glasgow Coma Scale ≤ 13/15) and in about 55% of survivors of aneurysmal subarachnoid hemorrhage. Some degree of hypopituitarism, most ...