Diseases of Hypothalamus and Pituitary

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Causes of Hypopituitarism

-Congenital ( Prader-willi, Hall-Pallister)
-Acquired

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

Craniopharyngioma

-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

Hypogonadism

-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
-idiopathic

Causes of hypothalamic dysfunction in males

-drugs, critical illness, idiopathic

Prolactinoma

-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?

-hyperprolactinemia

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
-kyphosis
-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

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