Chuong 26

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CMDT 2013

Endocrine Disorders Paul A. Fitzgerald, MD

cc

DISEASES OF THE HYPOTHALAMUS & PITUITARY GLAND ANTERIOR HYPOPITUITARISM ``

EssentialS of diagnosis

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. ``

``General Considerations 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. 1. Hypopituitarism caused by 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.

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Other types of mass lesions include granulomas (eg, ­g ranulomatosis with polyangiitis [formerly Wegener granulomatosis], tuberculosis), Rathke cleft cysts, apoplexy, metastatic carcinomas, aneurysms, and brain tumors (craniopharyngioma, meningioma, dysgerminoma, glioma, chondrosarcoma, chordoma of the clivus). Autoimmune hypophysitis, postpartum pituitary necrosis (Sheehan syndrome), eclampsia–preeclampsia, sickle cell disease, 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. 2. Hypopituitarism without mass lesions—This may be congenital in syndromes such as septo-optic dysplasia (de Morsier syndrome). Congenital hypopituitarism also develops in patients with PROP1 and other gene mutations. Hypopituitarism may also be caused by cranial radiation, surgery, encephalitis, hemochromatosis, or autoimmunity. It may also occur after coronary artery bypass grafting. 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 occurs in one-third of ischemic stroke patients, most commonly GH deficiency and hypogonadotropic hypogonadism. Mitotane, given for adrenal cortical carcinoma, can suppress TSH secretion and cause reversible secondary hypothyroidism. Therapy with exogenous corticosteroids (parenteral, oral, inhaled, or topical) can suppress adrenocorticotropic hormone (ACTH) secretion and causes functional isolated secondary adrenal insufficiency. Congenital isolated hypogonadotropic hypogonadism can be caused by various gene mutations that control the production or release of gonadotropin-releasing hormone (GnRH), LH, or FSH. Congenital adrenal hypoplasia (see below) is one cause of isolated hypogonadotropic hypogonadism. It may be autosomal recessive or X-linked; the X-linked form is caused by a mutation in the DAX 1 gene. Adrenal insufficiency, caused by failure to form the adrenal cortex, can present during infancy or childhood in boys with DAX 1 gene mutations. Prader-Willi syndrome


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