Pituitary tumor therapy

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Prolactinomas

most common pituitary tumor

  1. accounts for 30-40% of pituitary tumors, microadenomas tend to cause symptoms earlier in women and later in men
  2. symptoms: galactorrhea, amenorrhea, infertility, hirsutism, gynecomastia and erectile dysfunction in men, delayed puberty, reduced bone mineral density
  3. symptoms may also be caused by antipsychotic drugs, cirrhosis, primary hypothyroidism (because TRH stimulates prolactin), pregnancy
  4. levels of prolactin in a prolactinoma usually are > 200; if prolactin level is < 100 prolactinoma is less likely than stalk effect due to a loss of prolactin inhibiting factor (PIF a.k.a. dopamine) reaching the pituitary
  5. treatment: dopamine agonists such as bromocriptine (.625 mg/day to start), pergolide, cabergoline, typically get tumor shrinkage over 1 year
    1. recurrence rate after surgery of up to 40% but depends on size and location of lesion

Acromegaly

excessive growth hormone production

  1. occurs equally in males and females
  2. presents as a macroadenoma in 85% of cases
  3. symptoms: soft tissue hypertrophy, headache, arthritis, organomegaly, sleep apnea, increased risk of colon cancer (due to stimulation by IGF-1)
  4. lab test: elevated GH with failure to suppress with glucose administration, elevated IGF-1 (a.k.a. somatomedin-C), hyperprolactinemia from stalk compression and active secretion from tumor as GH and PRL secreting cells have a common precursor, hypercalciuria, nephrolithiasis, hypogonadism
  5. treatment: surgical is the primary option with a 80-90% cure rate in microadenomas and 35% cure with macroadenomas and a recurrence rate after initial cure of 10%
    1. secondary suppressive treatment is the somatostatin analog octreotide which binds to somatostatin receptor, decreases GH secretion and is associated with tumor shrinkage
    2. bromocriptine may also be used to decrease GH levels (response due to common precursor cell with PRL secreting cells)
    3. pegvisomant (competitive receptor antagonist) used for medical suppression outside US

Cushing’s disease

pituitary-driven excessive cortisol production

  1. Cushing’s disease refers to ACTH dependent Cushing’s syndrome caused by a pituitary adenoma
  2. symptoms: obesity, skin changes (easy bruising, thin skin, acne), hirsutism, menstrual irregularities, hypertension, proximal muscle weakness, osteoprorsis, glucose intolerance
  3. diagnosis: high and low dose dexamethasone suppression test and 24 urine cortisol collection
    1. confirm with high dose (2-6 mg q6) test where pituitary tumors will suppress but not ectopic ACTH tumors
  4. treatment of choice is surgery with goal of normalizing cortisol levels
  5. non-secreting tumors
  6. usually secrete gonadotropins (alpha or beta subunit only is common)
  7. account for 1/3 of all pituitary tumors
  8. macroadenomas can cause panhypopituitarism
  9. treatment: surgical with improvement in visual field in 70% and recurrence in 10-15%
    1. may give adjuvant radiation, somatostatin, or dopamine agonists

Thyrotropinomas

TSH producing tumors

  1. very rare
  2. typically present with hyperthyroxinemia and goiter
  3. labs: elevated T4 and T3, failure to suppress TSH with T3
  4. treatment: surgery with 40% cure rate, somatostatin analogs with 92% having suppression of TSH, radiation

Incidental pituitary adenoma

See Non functional pituitary tumor

  1. decision to treat is controversial, depends on size, pituitary function, threat to optic apparatus, and patient age/health
  2. most common tumor found incidentally at autopsy in the elderly is pituitary adenoma
  3. get follow up MRIs every 6-12 months
  4. pituitary apoplexy
    1. symptoms: sudden headache, visual change, opthalmoplegia and altered mental status caused by sudden hemorrhage or infarction of pituitary gland or an adenoma; if occurring in postpartum period it is called Sheehan’s syndrome
    2. following apoplexy, panhypopituitarism is very common
      1. with panhypopituitarism see adrenal insufficiency (hypotension, dizziness, weakness), hypothyroidism, gonadotropin deficiency (amenorrhea or erectile dysfunction), GH deficiency (decreased muscle mass), prolactin deficiency (no symptoms)
    3. treatment:surgery for mental status changes or rapid progression of symptoms or severe visual loss
      1. must give the patients stress dose steroids of hydrocortisone 100 mg q8 and electrolyte management
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