Hypothalamus and Pituitary

Question 1

Growth hormone def

Answer 1

• most important clinical manifestation of GHD is growth failure
• mediated by IGF-1
• circulating endogenous growth hormone lasts 20-30 minutes
• promotes longitudinal bone growth until epiphyseal closure

Question 2

Laron dwarfism

Answer 2

-primary GF deficiency
-severe postnatal growth
-GH receptor mutated gene
DX:
-inc circulating levels of GH and low IGF-1 and IGFBP-3

Question 3

Treatment for Laron syndrome

Answer 3

Mecasermin- recomb IGF-1

Side effect is hypoglycemia- take med w/ meal

Question 4

Prader- Willi syndrome

Answer 4

Deletion of genes from paternal chr 15

-growth failure, obesity, carb intolerance, mild-mod retardation

Question 5

Turner Syndrome

Answer 5

girls have 45 x karyotype

-rudimentary ovaries, growth hormone must be used to achieve max height

Question 6

Other indications for GH

Answer 6

aids, short bowel syndrome (pts dependent on parenteral nutrition)

Question 7

Toxicities of GH

Answer 7

Hyperglycemia, pseudotumor cerebri, inc risk of sleep apnea in prader willi syndrome
-arthralgias and myalgias, rarely carpal tunnel
contraindicated in individuals with active malignancy

Question 8

Mecasermin

Answer 8

-recomb IGF-1
Take med with carb containing meal because can cause hypoglycemia
-IGF1 deficiency
-Laron syndrome

Question 9

Acromegaly

Answer 9

large hands, large feet, frontal bossing, coarse facial features
glucose intolerance
-cardiac manifestations- LV hypertrophy, hypertension,
-GI- colon polyps
-elevated IGF-1

Question 10

Screening for Acromegaly

Answer 10

elevated IGF-1
Confirmation with post prandial growth hormone- should go down
MRI of brain- most radiologically visible

Question 11

Tx for acromegaly

Answer 11

transphenoidal surgery
33-75% success rate

• octreotide- somatostatin analogue- normalizes GH in 50% of pts by binding to GH receptor in pituitary adenoma–> tumor shrinkage in 50% of pts
• can cause gall stones
• parenteral administration

2nd line therapy- GH receptor blocking agents peripherally (does not decrease size of tumor)

Question 12

Pituitary apoplexia

Answer 12

Ischemic necrosis in enlarging adenoma

• comrpession of superior hypophysial artery against sellar diaphragm
• hemorrhage
• rapid enlargement and edema- acute pain, CN palsies, pituitary insuffiency

-if pt has low ACTH and low cortisol- they are in adrenal crisis

Question 13

Acute adrenal insufficiency

Answer 13

Need to treat right away
-Start steroids

Then treat with mineralocorticoids
Must triple steroid dose in times of acute stress

Question 14

Levothyroxine

Answer 14

hypothyroidism

taken 1 hr away from food

Question 15

Testosterone replacement

Answer 15

-do not give to young men who wish to bear children, untreated sleep apnea, prostate or breast cancer

Question 16

Prolactinoma

Answer 16

Lactoroph adenomas- produce prolactin
-very amenable to pharmacologic therapy

• more common in women
• premenopausal women- , galactorrhea, infertility, oligomenorrhea, amenorrhea

postmenopausal- larger prolactinomas, bitemporal hemianopsia, incidental

men- hypogonadism, dec libido, impotence, infertility, gynecomastia

Question 17

Cabergoline

Answer 17

Dopamine D2 receptor agonist

Used for shrinking pituiary prolactin secreting tumors, lowers circulating prolacin levels and restoring ovulation

Question 18

Bromocriptine

Answer 18

Dopamine agonist for prolactinomas

-can cause nausea and vomiting, headache, postural hypotension

Question 19

Diabetes insipidus

Answer 19

excessive thirst and excreion of large amts of diluted urine because of little ADH production

Tx with desmopressin (long lasting ADH analog for V2 receptor)

Question 20

Desmopressin

Answer 20

Tx for central diabetes insipidus

Can cause hyponatremia due to excessive reabsorption of water

Question 21

Nephrogenic diabetes insipidus

Answer 21

Problem with receptor for ADH

-no treatment available

Question 22

Vasopressin

Answer 22

responsible for regulating body’s retention of water by inc water absorption in collecting ducts (v2 receptor)
-inc peripheral vascular resistance which in turn increases arterial blood pressure (v1 receptor)

Question 23

Prolactin axis

Answer 23

Hypothalamus- thyrotropin releasing hormone (TRH) which is stimulatory
Dopamine- inhibitory

Pituiary- prolactin

Target organ- mammary gland

Question 24

Reproductive axis

Answer 24

Hypothalamus- GnRH
Pituitary- LH, FSH
Ovary or testis- estrogen, progesterone, testosterone

Inhibin from ovary and testes have inhibitory

Question 25

Thyroid axis

Answer 25

Hypothalamus- Thyrotropin releasing hormone (TRH)

Pituitary- TSH

THyroid- T3 and T4

Question 26

Adrenal axis

Answer 26

Hypothalamus- Corticotropin releasing hormone (CRH)

Pituiary- ACTH

ADrenal- glucocorticoids, mineralocorticoids, sex steroids