Pituitary Dysfunction Flashcards
What stimulates the release of growth hormone?
Sleep Puberty Glucagon Hypoglycemia Stress High levels of amino acids Alpha-adrenergic agonists
What suppresses the release of growth hormone?
Aging
Somatostatin
Hyperglycemia
Free fatty acids
Disorders in the HPA axis can be either central or peripheral. What does this mean?
Central disorders arise from problems in the hypothalamus or pituitary, while peripheral disorders arise from the target organ.
Describe the process of dynamic pituitary testing.
You use the natural stimulus for a hormone to induce secretion. If the natural stimulus does not elicit the expected response, then you know that hormone is somehow affected.
What organ secretes IGF-1?
The liver (in response to GH)
What is the best screening test for acromegaly?
IGF-1 levels
What three categories of treatment can help treat acromegaly?
- Surgical excision of the GH-secreting tumor
- Radiation therapy of the GH-secreting tumor
- Somatostatin analogues or GH antagonists
What happens to GH over the lifespan?
Its levels decrease by about 14% per decade.
Use of GH in those with adult-onset growth hormone deficiency has ________________.
not been shown to decrease fracture risk or improve longevity
_______________ tests can be used to test for GH reserves, but it is not done often because of its intrinsic danger.
Insulin-induced hypoglycemia
_______________ are more common in women and present with infertility and menstrual irregularities.
Prolactinomas
_______________ is used in all those with prolactinomas, except for in pregnant women who receive bromocriptine because of its favorable pregnancy safety profile.
Cabergoline
What can cause low prolactin levels?
Use of dopamine agonists or infiltrative neoplasms
Cushing’s disease can be either ____________ or _____________.
ATCH-dependent (75% of cases) or ACTH-independent (25%)
The nadir of cortisol usually occurs at _________, while the peak occurs at __________.
~midnight; ~8:00 AM
When should you test someone’s cortisol to test for Cushing’s syndrome?
Midnight (you have them chew a cotton ball and send it in)
What can cause adrenal insufficiency?
- Opioids
- Surgical removal of the pituitary
- Use of exogenous steroids (that then suppress the HPA axis)
When should you test cortisol levels for suspicion of adrenal insufficiency?
~8:00 AM
Most _____________ adenomas are silent because their secreted product is dysfunctional.
gonadotrope
What is apoplexy?
Sudden hemorrhage of the pituitary gland that leads to headache, ophthalmoplegia, and altered mental status
ADH is primarily released by _________________.
hyperosmolar states
_______________ occurs in about 20% of hospitalized patients.
SIADH
Two endocrine disorders can cause SIADH: _______________.
hypothyroidism and hypocortisolism
To fit the criteria for SIADH, people must have what two lab values?
Na less than 135 mEq/L and serum osmolarity less than 275 mEq/L
Which side of the pituitary is bigger?
The anterior side
Describe the nomenclature of primary, secondary, and tertiary in endocrine disorders.
Primary: target organ fails to respond to pituitary hormone
Secondary: pituitary fails to respond to hypothalamic hormone
Tertiary: hypothalamus fails to produce hormone
After administering glucose, levels of ____________ should be low.
growth hormone
Prolactin levels greater than _____________ are indicative of prolactinoma.
150 ng/mL
Low TSH and low T4 indicates _________.
central hypothyroidism
Thinking of the anterior pituitary, what is one reason it’s important for kids to get sleep?
Growth hormone secretion peaks during sleep
Excess FSH/LH is _______________.
rarely clinically evident
___________-adenomas are detected in over 80% of cases of acromegaly.
Macro
What can cause prolactinemia?
Use of D2 antagonists Primary hypothyroidism Suckling Stalk interruption (from a mass) Estrogen use TCAs Prolactinomas
Which layers of the adrenal cortex does ACTH act on?
All three
ADH deficiency is common in _____________.
metastatic cancer
Hypopituitarism presents with ________-kalemia.
hyper (due to loss of aldosterone from the deficient ACTH)
