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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.
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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%), 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; Rathke 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. The latter usually presents in youth with diabetes insipidus or hypopituitarism; osteolytic bone lesions are noted on radiographs.

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Lymphocytic hypophysitis is an autoimmune disorder that occurs during pregnancy or postpartum. It is characterized by pituitary infiltration by lymphocytes, macrophages, and plasma cells. About 25% of cases are associated with other autoimmune conditions, such as systemic lupus erythematosus (SLE). Hypophysitis can also be caused by chemotherapy with ipilimumab, an anti-CTLA4 monoclonal antibody that activates T-lymphocytes and enhances immunity. Affected individuals may present with headache, visual field impairment, or symptomatic hypopituitarism. The MRI appearance of hypophysitis is variable; it often appears as a homogeneous sellar mass that can extend above the sella (mimicking an adenoma). It usually results in ACTH deficiency but can cause deficiencies in any anterior pituitary hormone. The serum prolactin may be elevated if the lesion damages the pituitary stalk.

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2. Hypopituitarism without mass lesions
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Congenital hypopituitarism occurs in syndromes such ...

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