pituitary and hypothalamic disorders Flashcards
Anterior pituitary disorders?
- adenomas
- prolactinomas
- acromegaly
- gigantism
- panhypopituitarism
- cushing’s disease
Posterior pituitary disorders?
- SIADH
- Diabetes insipidus
What are the 2 main causes of pituitary gland disorders?
- hyperactivity
- hypoactivity
6 regulatory hormones of the hypothalamus?
- thyrotropin releasing hormone (TRH)
- gonadotropin releasing hormone (GnRH)
- corticotropin releasing hormone (CRH)
- growth hormone releasing hormone (GHRH)
- growth hormone inhibitory hormone (somatostatin)
- prolactin inhibiting hormone (PIH)
Major hormones of the anterior pituitary?
- FSH
- LH
- ACTH
- TSH
- Prolactin
- GH
FLAT PeG
Hormones of the posterior pituitary?
- ADH
- oxytocin
(both manufactured in the hypothalamus)
What holds the pituitary gland?
- the sella turcica
Presentations of pituitary tumors?
- hormonal abnormalities
- neuro sxs: HA, visual field impairment
- incidental finding on MRI obtained for another reason (incidentaloma)
What is an adenoma?
-a benign tumor of glandular tissue
Difference b/t microadenom and macroadenoma?
- microadenoma: tumor less than 10 mm in diameter, more common than macroadenomas (prolactinoma)
- macroadenoma: larger than 10 mm in diameter, may cause mass effect
etiologies of hyperprolactinemia?
- adenoma: most common cause of sellar region masses - prolactinoma is the most common type of pituitary adenoma
- trauma
- meds: SSRI’s, antipsychotics, cocaine, alpha methyldopa
- hypothyroidism
Why would a a prolactinoma lead to bitemporal hemianopsia?
- because it may cause compression of the optic chiasm
What is a prolactinoma a tumor of?
- the anterior pituitary
- secretes prolactin
What will happen if there is damage to the pituitary stalk?
- signals from the hypothalamus won’t be transmitted to pituitary
- so prolactin levels then increase unchecked
What meds that increase serotonin might lead to increased prolactin levels?
- antidepressants
- antipsychotics
- alpha methyldopa (aldomet -> antihypertensive)
- serotonin is a prolactin releasing factor
What may hypothyroidism cause?
- increased prolactin levels
- TRH from hypothalamus stimulates the release of TSH and prolactin
What kind of adenomas are more common in men? women?
- microadenomas more common in women ( 1 cm in size
- prolactin blocks gonadotropins FSH and LH
What sxs of prolactinoma will women present with?
- amenorrhea, galactorrhea and infertility (b/c of blocked secretion of FSH and LH)
What sxs of prolactinoma will men present with?
- decreased libido, gynecomastia, erectile dysfunction, infertility, bitemporal hemianopsia, headache, sxs due to decreased testosterone and mass effect from the tumor
What is the best lab test for dx of hyperprolactinemia? other tests?
- prolactin level: best initial test
- additional tests to rule out causes of secondary hyperprolactinemia (TSH, Beta-HCG, CMP, LH, FSH, serum estradiol (women), serum free and total testosterone (men)
- MRI to confirm dx
Rx Tx of hyperprolactinemia?
- cabergoline (best tolerated)
- Bromocriptine
Other tx options for hyperprolactinemia?
- transsphenoidal pituitary surgery for large sx tumors
- radiation therapy in some
- chemo with Temozolomide if no response to meds or radiation and if not a surgical candidate
What is acromegaly?
- anterior pituitary characterized by enlargement, thickening and broadening of bones - particularly extremities
What are the causes of acromegaly?
- hypersecreton of GH after fusio of epiphysis with shaft of bone
- adenomatous tumor of anterior pituitary involving acidophilic cells
signs and sxs of acromegaly?
- striking features are protrusion of:
supraorbital ridges, broadening of nose, thickening of lips, thickening and wrinkles formation on forehead, lower jaw (prognathism) - face with these features: referred to as acromegalic or gorilla face
- kyphosis: enlargement of hands and feet with bowing spine
- scalp is thickened and thrown into folds
- overgrowth of body hair
- visceral organs are enlarged
- thyroid, parathyroid and adrenal glands show hyperactivity
- hyperglycemia and glycosuria
- HA, HTN
- visual disturbance - bitemporal hemianopia
What is always the cause of acromegaly?
- pituitary tumor which causes an excess GH secretion
- most frequently occurs in ages 20-40
- may also be associated with tumors of pancreas or parathyroid glands
More signs and sxs of acromegaly?
- skeletal changes
- coarsening of facial features: jaw protrusion, prominent brow
- enlargement of hands and feet
- deepening of voice
- carpal tunnel syndrome
- CHF
- amenorrhea
- HAs
- visual field loss
- weakness
- organ enlargement
Why do acromegalics die at such a young age?
- because they suffer end-organ effects from HTN and abnormal glucose metabolism. 50% die
What is acromegalic gigantism?
- if GH is produced in excess prior to epiphyseal plate closure -> results in gigantism (occurs in childhood)
- acromegaly appears during adulthood
How is gigantism characterized?
- pituitary disorder characterized by:
excessive growth of body, average height is approximately 7-8 ft
Causes of gigantism?
- hypersecretion of GH in childhood or in pre-adult years
- tumor of acidophilic cells of anterior pituitary
Signs and sxs of gigantism?
- huge stature: 7-8 ft
- hyperglycemia, glycosuria, pituitary diabetes mellitus
- HA due to tumor of pituitary
- visual disturbance
- gigantism ends in hypopituitarism ( burning of cells of anterior pituitary)
Best initial test for dx acromegaly?
- IGF-1 level (insulin like growth factor)
- serum GH not suppressed following oral glucose load (75-100 g glucose) - acromegaly
- MRI: see pituitary in 90%
TOC for acromegaly/gigantism?
- surgical
- transphenoidal resection
- medical therapy: cabergoline (oral), or ocreotide, lanreotide, pegvisomant (subq injections)
- gamma knife radiosurger if they fail transsphenoidal surgery
Etiology of hypopituitarism?
- pituitary apoplexy: hemorrhage into pituitary gland
- sheehan’s syndrome: post partum pituitary ischemic necrosis
- infiltration: sarcoid, hemochromatosis, TB, syphilis
- non functioning adenoma
- trauma
- stroke
- mass effect
What is the first hormone deficiency to develop with lack of functioning pituitary?
- GH
- LH/FSH: 2nd
- TSH: 3rd
- ACTH: 4th
What sxs would a LH/FSH deficiency cause?
- amenorrhea, infertility, decreased pubic and axillary hair, genital atropy, decreased libido, erectile dysfunction
What sxs would a GH deficiency cause?
- increased abdominal fat, anxiety, depression, fatigue, decreased libido, decreased muscle mass, osteo (porous/penia), increased LDL, increased triglycerides
What sxs would a TSH deficiency cause?
- fatigue, wt gain, weakness, decreased appetite, cold intolerance
What sxs would a ACTH deficiency cause?
- fatigue, decreased appetite, decreased pigmentation, low BP, low glucose
Signs and sxs of congenital panhypopituitarism?
- micropenis
- midline defects
- optic atrophy
- hypoglycemia
- poor growth
What is a pituitary apoplexy?
- hemorrhage into pituitary
- usually secondary to existing adenoma
Sxs of pituitary apoplexy?
- acute sxs: HA, N/V, altered mental status, low BP, low blood glucose
- this is a rare endocrine emergency
What should you do if a pt presents with a pituitary apoplexy?
- stabilize, assessment of fluid and electrolyte balances, IV steroids
- acutely unwell pts should have a prompt neuro assessment
- surgery if severe ophtho signs or deteriorating mental status
What is sheehan’s syndrome?
- post partum ischemic necrosis of pituitary
- secondary to hypotension, emboli, HELLP syndrome
sxs of sheehan’s syndrome?
- difficulty breastfeeding, and extended amenorrhea
What is the best initial test for hypopituitary fxn?
- check anterior pituitary hormones:
LH/FSH
IGF-1 or GH insulin response test: admin insulin to lower blood glucose leve, and GH should increase due to insulin release - TSH
- ACTH: measured indirectly through cortisol levels
- MRI
Tx of hypopituitarism?
- address underlying cause
- replace needed hormones
- pituitary apoplexy may require surgical decompression
- intitial toc: IV steroids
What is Cushing’s disease usually associated with?
- obesity
Cause of cushing’s disease?
- hypersecretion of glucocorticoids: mainly cortisol
- either pituitary origin or adrenal origin
Difccerence b/t cushing’s disease and cushings syndrome?
- disease: specific to pituitary origin
- syndrome: not specific -> hypersecretion of glucocorticoids
Pituitary origin of Cushing’s disease?
- increased secretion of ACTH leads to hyperplasia of adrenal cortex therefore, hypersecretion of glucocorticoids takes place
- tumor in pituitary cells (basophilic cells)
Origin of ACTH increase in Cushing’s other than pituitary tumor?
- malignant tumor of nonendocrine origin like cancer of lungs or abdominal viscera
- hypothalamic disorder causing hypersecretion of corticotropin releasing hormone (CRH)
Signs and sxs of Cushing’s?
- disproportionate distribution of body fats results:
- moon face: fat accumulation and retention of water and salt
- torso: fat accumulation in chest and abdomen but slim legs and arms
- buffalo hump: fat deposit on back of neck and shoulder
- pot belly: fat accumulation in upper abdomen (with a lot of purple striae)
- purple striae: reddish purple stripes on abdomen: due to stretching of abdominal wall by excess subq fat, rupture of subdermal tissue due to stretching, defiency of collagen fibers due to protein depletion
- thinning of extremities
- thinning of skin and subq tissue: easy bruising
- darkening of skin on neck (aconthosis)
- pigmentation of skin
- facial redness (facial plethora)
- weakening of muscle
- facial hair growth (Hirsutism)
- bone resorption leads to osteoporosis
- hyperglycemia due to gluconeogenesis leads to adrenal diabetes and glycosuria
- HTN
- immunosuppression resulting in susceptibility for infection
- poor healing
What is SIADH (Syndrome of Inappropriate Antidiuretic hormone) characterized by?
- characterized by euvolomic hyponatremia due to elevated ADH levels:
reabsorption of excess fluid, low sodium, low serum osmolarity
What is euvolomic hyponatremia?
- normal body sodium with increase in total body water so looks hyponatremic
If SIADH is chronic what type of sxs will pt present with?
- most likely will be asx
- HA
- N/V
- altered mental status
- seizures
Causes of SIADH?
- TBI
- malignancy
- meningitis
- medications
Work up and dx of SIADH?
- CMP
- urine Na+ and osmolarity
- urine Na+ is inappropriately high (>20 mEg/L) with low serum Na (
Tx of SIADH?
- fluid restriction of 1200-1800 mL per day
- for sx pts (neuro manifestations):
- hypertonic saline (3%)
- don’t correct Na too quickly -> may cause central pontine myelinolysis: aka osmotic demyelination syndrome: results in destruction of myelin sheath covering nerve cells in the pons (middle brainstem): pretty much irreversible
What is the cause of diabetes insipidus?
- posterior pituitary disorder characterized by excess exretion of water through urination
-occurs due to lack of appropriate ADH levels:
central cause: deficiency of ADH (vasopressin), resistance to ADH
nephrogenic: defect in kidney tubules that interferes with water reabsorption
What is out of sync in diabetes insipidus?
- plasma and urine osmolarity are out of sync
- elevated plasma Na+ with an inability to concentrate the urine
Sxs of diabetes insipidus ?
- intense thirst (2-20 L/day)
- polydipsia
- craving for ice water
- polyuria, nocturia, enuresis
- hypernatremia
Polyuria sx of?
diabetest insipidus
- excretion of large quantity of dilute urine with increased frequency of voiding
- daily outpt: 4-12 L
- due to absence of ADH, epithelial cells of distal convulated tubule in nephron and collecting duct of kidney becomes impermeable to water
Polydipsia is a sx of what?
- sx of diabetes insipidus
- intake of excess water
- because of polyuria, thirst center in hypothalamus results in intake of large quantity of water
Dehydration is sx of what?
- diabetes insipidus
- in some cases thirst center in hypothalamus is also affected by a lesion
- therefore water intake decreases in these pts and the loss of water through urine isn’t compensated
Causes of diabetes insipidus?
- develops due to deficiency of ADH which occurs in following conditions:
1. lesion (injury) or degradation of supraoptic and paraventricular nuclei of hypothalamus
2. lesion in hypothalamo-hypophyseal tract
3. atrophy of posterior pituitary
4. inability of renal tubules to give response to ADH hormone. Called Nephrogenic diabetic insipidus
Etiology of diabetes insipidus?
- central: most common!!
due to trauma or tumor, may be idiopathic, cerebral anoxia, meningitis, radiation - nephrogenic: meds: lithium, demeclocycline (tetracycline), hypercalcemia, hypokalemia, infiltrative disease, sjogren’s syndrome (AI disorder)
Work up of dx diabetes insipidus?
- CMP (includes serum Na)
- plasma osmolarity
- plasma ADH
- urine Na and osmolarity
- water deprivation test: serum Na will continue to increase and urine Na will still be low
- DDAVP (demopressin.. synthetic replacement for vasopression, the hormone that reduces urine production) test: urine Na should increase if central DI
Tx of diabetes insipidus?
central: best tx is DDVAP
(oral or nasal spray)
nephrogenic: hydrochlorothiazide or amiloride (diuretic)
- block reabsorption of Na in the kidneys to keep plasma Na down some
