Pituitary tumors Flashcards
1
Q
Prolactinomas
A
- Most common pituitary tumor
- Pituitary tumors can be functional or non-functional (adenomas), w/ both types manifesting as pressure Sxs and functional ones manifesting as changes in certain hormones
- Prolactinomas can be micro (1cm)
- Microadenomas typically produce a serum prolactin level of 100ng/ml
- On MRI if there is a macro adenoma but the prolactin level is <100ng/ml then the tumor is nonfunctional and the prolactin level is due to stalk effect from the tumor (removing DA inhibition of prolactin release)
2
Q
Causes of hyperprolactinemia
A
- Physiologic: pregnancy (most common cause), nipple stimulation, stress
- Pathologic: prolactinoma, other tumors (GH secreting), stalk effect, inflammatory d/o (sarcoidosis), renal insufficiency, drugs, hypothyroidism
- Hypothyroidism must be ruled out before proloactinoma is considered: hypothyroidism causes enlargement of pituitary and can lead to increased prolactin levels
- Drugs that can cause hyperprolactinemia: antihypertensives (verapamil), GI drugs (anti GERD/anti emetics), antipsychotics and antidepressants
3
Q
Signs and Sx of prolactinomas
A
- In women (tend to be micro): oligo/amenorrhea, galactorrhea, infertility
- Women present w/ less pressure Sx b/c usually are microadenomas
- High prolactin levels inhibits LH secretion and leads to estrogen deficiency, causing the amenorrhea and hot flashes/vaginal dryness
- In post menopausal women micro adenomas rarely cause any problems since they are already estrogen deficient and they usually do not have galactorrhea
- In men (more likely to have macro adenomas) there is more likely to be suprasellar extension and thus pressure on the optic chiasm
- This typically results in bitemporal hemianopsia
- Men also have decreased testosterone levels (due to suppressed LH) and thus may present w/ decreased libido, impotence, lack of pubic hair (chest, face, axilla), anemia (due to low T-> low EPO)
4
Q
DDx of suprasellar mass
A
- Pituitary adenoma
- rathke’s cleft cyst
- Craniopharyngioma
- Meningioma
- Other: sarcoid, granuloma, CA
- 55% of pituitary adenomas are nonfunctional, 22% produce prolactin, 12% GH, 11% ACTH, .4% TSH
5
Q
Pressure effects
A
- Usually associated w/ macro adenomas
- Headaches
- Vision changes: visual field abnormalities, decrease in visual acuity, cranial nerve palsies
- Pituitary insufficiency (pan hypo pit)
6
Q
Hypopituitarism from stalk effect
A
- Nonfunctioning macro adenomas can present w/ hormone deficiency and/or excess b/c the stalk is damaged and the releasing hormones/DA cannot get to the pituitary
- Non-essential hormones are lost first, essential ones are conserved
- Most are GH, LH, FSH deficient
- LH deficiency can also cause anemia in men, since EPO action is related to testosterone levels
- Most retain ACTH, TSH
- Many are hyperprolactinemic (due to disinhibition of DA)
7
Q
Manifestations of hormone hypersecretion
A
- Prolactinoma: impotence, infertility, amenorrhea, galactorrhea
- Somatotroph: acromegaly (don’t use GH levels, use IGF1 levels for Dx)
- Can also do oral glc test: give glc and measure GH levels, in acromegaly the GH levels will remain constant, in normal pt the GH levels will drop upon glc load
- Corticotroph: cushings
- Thyroitroph: hyperthyroidism
8
Q
Acromegaly and mortality
A
- Acromegaly is a very chronic, long term disease that produces severe morbidities
- Usually due to GH producing pituitary tumors
- Most pts die of cardiac disease
- Colon CA has a high prevalence in acromegaly pts
- Check IGF levels (best test) and do oral glc tolerance test
- Do not use GH levels
- Rx: somatostatin analogues or GH receptor antagonists (pegvisomant)
- Post op: check IGF1 and OGTT for remission
9
Q
Management for functioning tumors
A
- Surgery is cornerstone for ACTH, GH, TSH, and some prolactinomas (when pt is intolerant to DA agonist)
- Tumors causing cushings: most are micro
- Tumors causing acromegaly: most are macro
- Prolactinoma: depends on sex (women its micro, men its macro)
- Possibly radiation
- Medication: DA agonist is 1st line Rx for prolactinoma since they inhibit prolactin secretion
10
Q
Post op after tumor resection
A
- Cushings: check cortisol after overnight dexamethasone infusion
- Cortisol drops sufficiently (<2 mcg/dl) then the pt is cured
- Acromegaly: GH should be around 1ng/ml after 24hrs (short T1/2)
- IGF will take a while (wks-mos) to fall b/c T1/2 is longer
- Prolactin levels can be measured at 24 hrs, should be around 1ng/ml
11
Q
Complications of surgery
A
- CSF leak (use glc test to see if its CSF of mucous)
- Meningitis
- Intrasellar hemorrhage
- Hypopituitarism due to injury to intact gland
- DI can occur when there is damage to the stalk or posterior pit
12
Q
DI after pituitary surgery
A
- DI can be noticed if urine output is >300ml/hr for 2 consecutive hours, then get urine SG and serum Na
- Urine SG will be low (w/ low urine Na), serum Na will be high
- Pt will want to drink a lot (no thirst, no DI)
- Must rule out free water excretion due to something else (low GH)
- Most DI is transient (lasts 1 day, permanent DI more common w/ craniopharyngiomas or rathke’s cleft cysts)
- May also see SIADH, due to a combination of removing pressure on the pituitary and the transient DI
- DI causes hypernatremia, and the loss of pressure may cause the post pit to over secrete ADH in an attempt to rectify the hypernatremia
- If severe may get hyponatremic
13
Q
Medical management of prolactinomas
A
- DA agonists: bromocriptine and cabergoline
- 1st line Rx
- Severe side effects may limit pt ability to tolerate
- Side effects include nausea, fatigue, postural hypotension, nightmares
- Pts w/ macroadenomas will be on these drugs for life
- Women w/ micro adenomas may stop Rx upon menopause
14
Q
Medical management of cushings
A
-Inhibitors of cortisol synthesis: ketoconazole, metyrapone, mefipristone
15
Q
Medical management of acromegaly
A
- Somatostatin analogues: octreotide, lanreotide
- GH antagonists: pegvisomant
