Week 3: pituitary Tumors

Question 1

Non functioning tumors/pituitary tumors

Answer 1

• most common tumors of pituitary
• mainly present with pressure symptoms
• bilateral hemianopsia: from compression of optic chasm
• ocular palsies if there is extension of tumor into cavernous sinus
• hormone deficiencies (GH first then gonadotropins) or excess (prolactin -from stalk effect)

Question 2

Evaluation of nonfunctioning tumors

Answer 2

• MRI is imaging of choice

- must tests for hormonal deficiencies and excesses

Question 3

Prolactinomas

Answer 3

• commonest pituitary tumors
• more common in women
• micro or macro adenomas
• elevated serum prolactin

Question 4

Differential dx for hyperprolactinemia

Answer 4

Physiologic
-pregnancy, nipple stimulation, stress
Pathologic
-prolactinomas
-stalk effect from other tumors
-other functioning tumors (e.g. GH)
-inflammatory diseases
-stalk section trauma
-chest wall injury and irritation
-chronic renal failure
-drugs: antihypertensives, antipsychotics, GI drugs, antidepressants
-hypothyroidism

Question 5

clinical manifestations of hyperprolactinemia

Answer 5

• in premenopausal women: oligo/amenorrhea, galactorrhea, and infertility. Also hot flashes and vaginal dryness due to estrogen suppression
• if micro adenomas, no pressure symptoms
• post menopausal women: usually no symptoms with microprolactinomas
• men: pressure effects, testosterone deficiency symptoms such as decrease in libido, impotence, and infertility

Question 6

Ddx of sellar masses

Answer 6

• pituitary adenoma
• Rathke’s cleft cyst
• craniopharyngioma
• meningioma
• other really rare things such as sarcoid, pituitary carcinoma

Question 7

Diagnostic evaluation of prolactinoma

Answer 7

• serum prolactin level over 100ng/mL. One above 200 ng/ml is virtual assurance of diagnosis
• MRI should be done if there is elevation in serum prolactin

Question 8

Growth hormone producing tumors

Answer 8

• 1/3 of pituitary tumors
• causes acromegaly or giantism, but most commonly acromegaly
• clinical manifestations result from increased serum levels of IGF-1
• acromegaly develops slowly, over years: thick hands, prominence of jaw, change in bite, arthritic symptoms
• pressure symptoms for macro adenomas
• cardiovascular disease often cause of morbidity and mortality

Question 9

Diagnostic evaluation of acromegaly

Answer 9

• use IGF-1 serum levels, which vary by age
• glucose loading test: give oral glucose, which should result in GH suppression in normal individuals 90-120 mins after ingestion. but in acromegaly, GH remains unsurpressed

Question 10

management of functioning tumors

Answer 10

1. surgery for ACTH, GH, TSH and some prolactinomas
   - depends on tumor size and invasion
   - if invasion, surgery is less curative
2. radiation as adjective rx
3. medication
   - dopamine agonists for prolactinomas: bromocriptine, cabergoline
   - cushings: inhibitors of cortisol synthesis: ketoconazole, metyrapone, mefipristone
   - acromegaly: somatostatin analogs: octreotide, lanreotide
   - GH antagonists peripheral: pegvisomant

Question 11

Postoperative assessment of cure of pituitary tumors

Answer 11

1. Cushings
   - overnight de with 1mg. If cortisol is less than 2mcg/dl, 90% success
2. Acromegaly
   - GH at 24 hours since has short half life, can be checked the next day. 90% cure if less than 1 ng/mL
   - IGF-1 checked in 3+ weeks since long half life
3. prolactinoma
   - check prolactin at 24 hours, ~1 ng/mL, 90% cure

Question 12

Endocrine complications in post-op pituitary patients

Answer 12

• Diabetes insipidus: transient mostly. must differentiate from free water excretion, such as in GH tumors that are treated. Low GH cases diuresis. Can cause hypernatremia.
• SIADH: lots of release of ADH due to pituitary damage or overcompensation and decompression of the pituitary, leading to hyponatremia