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Diseases of Hypothalamus and Pituitary

Causes of Hypopituitarism
-Congenital ( Prader-willi, Hall-Pallister)
Acquired causes of hypopituitarism
1. Pituitary and or hypothalamic neoplasms
2. Trauma
3. Cranial radiation
4. Sheehan's syndrome
5. Infiltrative processes
6. Pituitary apoplexy (emergent action required)
1. Pituitary and/or hypothalamic neoplasms
-about 89% of all cases of hypopit. in adults
1. Pituitary Adenoma is the most common cause of hyposecretion of pituitary hormones in adults**
2. other adult tumors: craniopharyngioma and meningioma
3. in children-Craniopharyngioma, germinoma, eosinophilic granuloma
Mechanism of pituitary adenoma
-exert pressure on pituitary cells
-surgical removal my relieve pressure and restore cell funtion, but may also remove normal pituitary tissue causing more dysfunction
-arises from primitive mouth cavity
-cysts that contain oily, cholesterol like material; "machine oil"
2. Trauma
-neurosurgery to remove pit. or hypothal. tumor
-fracture at skull base that severs hypothalamic pit. stalk
3. Cranial radiation
-children more so affected
-deficiencies present years after radiation
4. Sheehan's syndrome
-infarction of the pituitary following postpartum bleeding which is so severe that hypotension (shock) develops, requiring need for blood transfusions
5. Infiltrative processes
-lymphocytic hypophysitis
-sarcoidosis (granulomas that affect hypothalamus typically)
Lymphocytic hypophysitis
-inflammation in the pituitary
6. Pituitary apoplexy
-acute expansion of pituitary gland from infarction or hemorrhage
-typically causes by hemorrhage into pre-existing pituitary adenoma
Clinical Presentation of Hypopituitarism
-manifestations depend on which hormone is deficient
-see following
-decreased FSH /LH
-Females: ovarian hypofunction and decreased estradiol; oligo or amenorrhea; infertility
-Males: testicular hypofunction and decreased testosterone; decreased libido; infertility
GH deficiency
-Children: short stature
-Adults: abnormal body composition with increased fat and decreased muscle; dyslipidema with cardiac complications (need confirmation)
TSH deficiency
-Decreased basal metabolic rate
-Decreased activity of sympathetic nervous system: weight gain, bradycardia, cold intolerance, thin/coarse hair, dry skin, mental slowing and depression
-In children will causes growth retardation
Prolactin deficiency
-inability to lactate after delivery
ACTH deficiency
-effects result from decreased cortisol release from adrenal cortex
-mild, chronic decrease in cortisol: fatigue, weakness, anorexia, weight loss, nausea, hypoglygemia
-severe, acute decrease in cortisol: shock
Causes of hypothalamic dysfunction in females
-anorexia, extreme exercise, stress, starvation, critical illness
Causes of hypothalamic dysfunction in males
-drugs, critical illness, idiopathic
-prolactin secreting pituitary tumor
-macroadenoma = or > 1 cm; may have mass effect
-microadenoma < 1 cm (much more common in females)
What is the most common pituitary hormone hypersecretion syndrome in males and females?
Drugs as a cause of hyperprolactinemia
-decrease/block binding of prolactin inhibiting factor (PIF) to dopaminergic receptors
-certain antipsychotic drugs
Clinical features of Gigantism
-increased height (8 ft or taller)
-Prominent jaw; enlarged hands and feet
-behavioral and visual problems
Clinical features of Acromegaly
-soft tissue swelling
-carpal tunnel syndrome
-joint symptoms due to enlargement of synovial tissue and cartilage
-enlargement of heart, thyroid gland
-symptoms assoc with hyperprolactinemia if pit adenoma secretes both GH and prolactin
Clinical complications of acromegaly
-life expectancy 10 years or less unless GH levels are controlled
-major cause of morbidity and mortality are cardiovascular: cardiomyopathy, LVH, HTN, arrhythmias, heart failure
-other complications: DM and cancer of GI
adrenal hyperplasia
-nonneoplastic increase in size due to increased proliferation of cells