pituitary and hypothalamic disorders Flashcards
1
Q
Anterior pituitary disorders?
A
- adenomas
- prolactinomas
- acromegaly
- gigantism
- panhypopituitarism
- cushing’s disease
2
Q
Posterior pituitary disorders?
A
- SIADH
- Diabetes insipidus
3
Q
What are the 2 main causes of pituitary gland disorders?
A
- hyperactivity
- hypoactivity
4
Q
6 regulatory hormones of the hypothalamus?
A
- 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)
5
Q
Major hormones of the anterior pituitary?
A
- FSH
- LH
- ACTH
- TSH
- Prolactin
- GH
FLAT PeG
6
Q
Hormones of the posterior pituitary?
A
- ADH
- oxytocin
(both manufactured in the hypothalamus)
7
Q
What holds the pituitary gland?
A
- the sella turcica
8
Q
Presentations of pituitary tumors?
A
- hormonal abnormalities
- neuro sxs: HA, visual field impairment
- incidental finding on MRI obtained for another reason (incidentaloma)
9
Q
What is an adenoma?
A
-a benign tumor of glandular tissue
10
Q
Difference b/t microadenom and macroadenoma?
A
- microadenoma: tumor less than 10 mm in diameter, more common than macroadenomas (prolactinoma)
- macroadenoma: larger than 10 mm in diameter, may cause mass effect
11
Q
etiologies of hyperprolactinemia?
A
- 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
12
Q
Why would a a prolactinoma lead to bitemporal hemianopsia?
A
- because it may cause compression of the optic chiasm
13
Q
What is a prolactinoma a tumor of?
A
- the anterior pituitary
- secretes prolactin
14
Q
What will happen if there is damage to the pituitary stalk?
A
- signals from the hypothalamus won’t be transmitted to pituitary
- so prolactin levels then increase unchecked
15
Q
What meds that increase serotonin might lead to increased prolactin levels?
A
- antidepressants
- antipsychotics
- alpha methyldopa (aldomet -> antihypertensive)
- serotonin is a prolactin releasing factor
16
Q
What may hypothyroidism cause?
A
- increased prolactin levels
- TRH from hypothalamus stimulates the release of TSH and prolactin
17
Q
What kind of adenomas are more common in men? women?
A
- microadenomas more common in women ( 1 cm in size
- prolactin blocks gonadotropins FSH and LH
18
Q
What sxs of prolactinoma will women present with?
A
- amenorrhea, galactorrhea and infertility (b/c of blocked secretion of FSH and LH)
19
Q
What sxs of prolactinoma will men present with?
A
- decreased libido, gynecomastia, erectile dysfunction, infertility, bitemporal hemianopsia, headache, sxs due to decreased testosterone and mass effect from the tumor
20
Q
What is the best lab test for dx of hyperprolactinemia? other tests?
A
- 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
21
Q
Rx Tx of hyperprolactinemia?
A
- cabergoline (best tolerated)
- Bromocriptine
22
Q
Other tx options for hyperprolactinemia?
A
- 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
23
Q
What is acromegaly?
A
- anterior pituitary characterized by enlargement, thickening and broadening of bones - particularly extremities
24
Q
What are the causes of acromegaly?
A
- hypersecreton of GH after fusio of epiphysis with shaft of bone
- adenomatous tumor of anterior pituitary involving acidophilic cells
25
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
26
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
27
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
28
Why do acromegalics die at such a young age?
- because they suffer end-organ effects from HTN and abnormal glucose metabolism. 50% die
29
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
30
How is gigantism characterized?
- pituitary disorder characterized by:
| excessive growth of body, average height is approximately 7-8 ft
31
Causes of gigantism?
- hypersecretion of GH in childhood or in pre-adult years
| - tumor of acidophilic cells of anterior pituitary
32
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)
33
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%
34
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
35
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
36
What is the first hormone deficiency to develop with lack of functioning pituitary?
- GH
- LH/FSH: 2nd
- TSH: 3rd
- ACTH: 4th
37
What sxs would a LH/FSH deficiency cause?
- amenorrhea, infertility, decreased pubic and axillary hair, genital atropy, decreased libido, erectile dysfunction
38
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
39
What sxs would a TSH deficiency cause?
- fatigue, wt gain, weakness, decreased appetite, cold intolerance
40
What sxs would a ACTH deficiency cause?
- fatigue, decreased appetite, decreased pigmentation, low BP, low glucose
41
Signs and sxs of congenital panhypopituitarism?
- micropenis
- midline defects
- optic atrophy
- hypoglycemia
- poor growth
42
What is a pituitary apoplexy?
- hemorrhage into pituitary
| - usually secondary to existing adenoma
43
Sxs of pituitary apoplexy?
- acute sxs: HA, N/V, altered mental status, low BP, low blood glucose
- this is a rare endocrine emergency
44
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
45
What is sheehan's syndrome?
- post partum ischemic necrosis of pituitary
| - secondary to hypotension, emboli, HELLP syndrome
46
sxs of sheehan's syndrome?
- difficulty breastfeeding, and extended amenorrhea
47
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
48
Tx of hypopituitarism?
- address underlying cause
- replace needed hormones
- pituitary apoplexy may require surgical decompression
- intitial toc: IV steroids
49
What is Cushing's disease usually associated with?
- obesity
50
Cause of cushing's disease?
- hypersecretion of glucocorticoids: mainly cortisol
| - either pituitary origin or adrenal origin
51
Difccerence b/t cushing's disease and cushings syndrome?
- disease: specific to pituitary origin
| - syndrome: not specific -> hypersecretion of glucocorticoids
52
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)
53
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)
54
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
55
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
56
What is euvolomic hyponatremia?
- normal body sodium with increase in total body water so looks hyponatremic
57
If SIADH is chronic what type of sxs will pt present with?
- most likely will be asx
- HA
- N/V
- altered mental status
- seizures
58
Causes of SIADH?
- TBI
- malignancy
- meningitis
- medications
59
Work up and dx of SIADH?
- CMP
- urine Na+ and osmolarity
- urine Na+ is inappropriately high (>20 mEg/L) with low serum Na (
60
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
61
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
62
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
63
Sxs of diabetes insipidus ?
- intense thirst (2-20 L/day)
- polydipsia
- craving for ice water
- polyuria, nocturia, enuresis
- hypernatremia
64
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
65
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
66
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
67
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
68
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)
69
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
70
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
