16. Acromegaly and Hyperprolactinemia

Question 1

acromegaly and hyperprolactinemia are both due to problems with what part of the endocrine system?

Answer 1

pituitary gland (specifically anterior pit)

Question 2

what are some physical exam findings of acromegaly?

Answer 2

coarse facial features, prominent brow, large tongue, doughy hands, small goiter, skin tag on back, normal strength and reflexes, small/soft testes

Question 3

why might some pts with acromegaly have poor sleep?

Answer 3

enlarged tongue causes sleep apnea

Question 4

how would you test whether GH release is due to a primary or secondary cause?

Answer 4

glucose load -> should suppress GH release.
If primary, GH release is not dependent on upstream signals, will not suppress with glucose
If secondary, GH release is responding to signals, should suppress with glucose load.

Question 5

GH vs IGF1: which is better to measure in serum for status of GH release?

Answer 5

best to measure serum IGF-1, since GH oscillates naturally over 24 h period. IGF1 has longer half life.

Question 6

three therapeutic options for acromegaly?

Answer 6

surgery, radiation, medical therapy

Question 7

describe the surgical options for acromegaly

Answer 7

transnasal adenectomy (removal of the tumor through the nose)
subfrontal craniotomy (through the skull if needed for large tumors)

Question 8

when would we recommend radiation as treatment for acromegaly?

Answer 8

if tumor has invaded the cavernous sinus, dangerous to remove surgically

Question 9

what drug therapy do we have for acromegaly?

Answer 9

dopaminergic agonists (bromocryptine, cabergoline)
long-acting somatostatin analog (octreotide)

Question 10

why would a dopamine analog work in reducing a GH releasing tumor?

Answer 10

the cells for prolactin and GH originate from the same line embryologically, share suppressibility by dopamine

Question 11

secondary v primary amenorrhea?

Answer 11

primary: someone who is the age that they should be menstruating, but has never started
secondary: once menstruated, but has now stopped.

Question 12

what is the most common cause of secondary amenorrhea?

Answer 12

pregnancy! don’t forget to check beta-hCG

Question 13

if menopause, what would be levels of gonadotropins?

Answer 13

HIGH

Question 14

a cause of hyperprolactinemia that does not concern the Prolactin axis?

Answer 14

hypothyroid.
pathway: thyroid hormones (T4, T3) are decreased, so TRH is not suppressed
excessive TRH yields hyperprolactinemia

Question 15

Prolactin: 2 major functions?

Answer 15

stimulate breast milk

disable pregnancy when lactating (via inhibiting GnRH release, causing gonad insensitivity to LH)

Question 16

Hyperprolactin: presentation in females?

Answer 16

galactorrhea, mens irregularity, infertility

Question 17

Hyperprolactin: presentation in males?

Answer 17

galactorrhea, visual field abnl, headache, impotense, EOM paralysis, ant pit malfunction
(men tend to present later, with bigger tumor, with more sx)

Question 18

most common cause of hyperprolactin?

Answer 18

pituitary tumor: prolactinoma

Question 19

Prolactinoma: three sequelae?

Answer 19

• infertility
• osteoporosis due to lack of estrogen
• mass effects of tumors (neuro)

Question 20

Prolactinoma: treatment options?

Answer 20

• surgical
• medical with long-acting dopa agonists)
• radiation

Question 21

Prolactinoma; what is preferred treatment?

Answer 21

med treatment. surgical removal tends to fail after several years with tumor recurrence.
meds are usually Preg X, so some women will do surgery in order to reduce tumor for a few years and avoid meds when preg, then begin meds when tumor recurs

Question 22

describe the embryological lineage of pituitary endocrine cells. what precursors give rise to what endocrine cells? what transcription factors are involved?

Answer 22

Precursor 1 yields ACTH cells
tsn factor PROP1 yields Precursor 2
Precursor 2 yields FSH/LH cells
tsn factor Pit1 yields Precursor 3
Precursor 3 yields TSH cells and GH cells
GH yields PRL cells

Question 23

If there is a mutation in the transcription factor PROP1, what ant pit cells would still be made?

Answer 23

only ACTH cells

Question 24

If there is a mutation in Pit1 transcription factor, what ant pit cells would be made/what would be absent?

Answer 24

Present: ACTH, FSH/LH cells
Absent: TSH, GH, PRL cells