OnlineMedEd: Endocrine - "Anterior Pituitary"

Question 1

Why does the posterior pituitary not fit into the H-P-X axis?

Answer 1

The posterior pituitary is a continuation of the hypothalamus, so it does not require an intermediary hormone from the hypothalamus.

Question 2

Review the anterior pituitary hormones from most-to-least necessary.

Answer 2

• ACTH
• TSH
• GH
• FSH/LH

Question 3

List the hypothalamic hormones, their pituitary counterparts, their target organs, and the final hormone.

Answer 3

• CRH -> ACTH -> adrenal glands -> cortisol
• TRH -> TSH -> thyroid gland -> T4
• GHRH -> GH -> liver -> IGF1
• GRH -> FHS/LH -> gonads -> testosterone/estrogen

Question 4

Describe the presentations of prolactinomas in men and women.

Answer 4

• Women: secondary amenorrhea, galactorrhea; microadenomas because caught early
• Men: decreased libido, bitemporal hemianopsia; macroadenomas caught late

Question 5

How should you work up suspected prolactinoma?

Answer 5

• First, review medications for dopamine antagonists
• Second, check a TSH and prolactin level. (Dustyn says to do these as separate steps, but I think in real life you do both at once.)
• Third, do an MRI for tumor if prolactin levels high

Question 6

True or false: prolactinomas are not usually treated surgically.

Answer 6

True

Cabergoline is the mainstay treatment. Bromocriptine can also be used but has a worse side effect profile.

Question 7

____________-thyroidism can cause prolactinemia.

Answer 7

Hypo

TRH stimulates the release of prolactin. Hypothyroidism causes increased TRH release.

Question 8

Describe the different presentations of acromegaly based on age.

Answer 8

• Kids: gigantism

* Adults: growth of hands, feet, face, visceral organs, and diabetes (because GH stimulates glucose production)

Question 9

_____________ usually causes death in those with acromegaly.

Answer 9

Diastolic heart failure (because of heart growth)

Question 10

To work up acromegaly, start with ___________.

Answer 10

IGF-1 levels

If this is elevated, do a glucose suppression test.

If the glucose suppression is also positive, then do an MRI.

Question 11

List the two treatments for acromegaly.

Answer 11

• Surgery

* Octreotide

Question 12

What vital sign abnormalities will you see in hypocortisolism?

Answer 12

• Hypotension

* Tachycardia

Question 13

The three groups of causes of acute hypopituitarism are _______________.

Answer 13

infection, infarction, and iatrogenic

Question 14

Apoplexy is usually caused by ____________.

Answer 14

a tumor that causes an infarction

Question 15

In cases of chronic hypopituitarism, the body diverts pituitary resources to _____________.

Answer 15

ACTH and TSH (at the expense of GH, FSH, and LH)

Question 16

Those with chronic hypopituitarism usually complain of ______________.

Answer 16

decreased libido, amenorrhea, or fatigue (because the body tries to preserve ACTH)

Question 17

Explain how the insulin stimulation test can diagnose hypopituitarism.

Answer 17

If you give insulin, the body responds by raising the blood sugar with GH and cortisol. If the person cannot make these they will become hypoglycemic with low doses of insulin.

Question 18

What is empty sella syndrome?

Answer 18

A normal anatomic variant in which the pituitary is above the sella (where it normally would be), discovered incidentally

Question 19

What are some causes of chronic hypopituitarism?

Answer 19

• Autoimmune disease
• Infiltrative disease (sarcoidosis, amyloidosis)
• Slow growing tumors