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DISEASES OF THE HYPOTHALAMUS & PITUITARY GLAND

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ANTERIOR HYPOPITUITARISM

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ESSENTIALS OF DIAGNOSIS

  • Partial or complete deficiency of one or any combination of anterior pituitary hormones.

  • Adrenocorticotropic hormone deficiency: reduced adrenal secretion of cortisol and epinephrine; aldosterone secretion remains intact.

  • Growth hormone (GH) deficiency: short stature in children; asthenia, obesity, and increased cardiovascular risk in adults.

  • Prolactin deficiency: postpartum lactation failure.

  • Thyroid-stimulating hormone (TSH) deficiency: secondary hypothyroidism.

  • Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) deficiency: hypogonadism and infertility in men and women.

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General Considerations
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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.

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Table Graphic Jump Location
Table 26–1.Pituitary hormones.
++ 1. Hypopituitarism with mass lesions
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Lesions in the hypothalamus, pituitary stalk, or pituitary can cause hypopituitarism. Pituitary adenomas can cause anterior hypopituitarism but rarely cause diabetes insipidus. Pituitary adenomas are usually sporadic but sometimes arise as part of multiple endocrine neoplasia (MEN) types 1 or 4. Pituitary tumors that arise in MEN 1 usually secrete prolactin (63%), growth hormone (GH) (9%), or both (10%) and are more aggressive than sporadic adenomas. Other mass lesions include granulomas, such as granulomatosis with polyangiitis (formerly Wegener granulomatosis), tuberculosis, cholesterol granuloma; cleft cysts; pituitary apoplexy; metastatic carcinomas or hematologic malignancies; aneurysms; and brain tumors (craniopharyngioma, meningioma, dysgerminoma, glioma, chondrosarcoma, chordoma of the clivus). Rare causes include postpartum pituitary necrosis (Sheehan syndrome), African trypanosomiasis, and Langerhans cell histiocytosis. Rathke cleft cysts are common embryonal remnants of Rathke pouch and are usually asymptomatic. However, they can enlarge and cause headache, visual field defects, anterior hypopituitarism, and diabetes insipidus.

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Lymphocytic hypophysitis is an autoimmune disorder that is more common in women (71%) and is associated with pregnancy in 11% of cases. It is characterized by infiltration of the infundibulum and pituitary by lymphocytes, macrophages, and plasma cells. Nearly 20% of cases are associated with other autoimmune conditions, such as systemic lupus erythematosus (SLE). Hypophysitis can also be caused by chemotherapy with ipilimumab. It typically presents with hypogonadotropic hypogonadism (62%), diabetes insipidus (54%), headache (50%), hypothyroidism (48%), adrenocorticotropic hormone (ACTH) deficiency (47%), growth hormone (GH) deficiency (37%), and hyperprolactinemia (36%), making clinicians often mistake it for a prolactinoma.

++ 2. Hypopituitarism without mass lesions
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Congenital hypopituitarism occurs in syndromes such as septo-optic dysplasia (de Morsier syndrome) and in patients with various gene mutations...

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