Endocrine pharamacology

Question 1

What is the action of hypothalamic hormone somatostatin ?

Answer 1

It inhibits growth hormone and thyroid-stimulating hormone release from the pituitary.

Question 2

What is the action of
Gonadotrophin-releasing hormone ?

Answer 2

It causes follicle stimulating hormone (FSH) and luteinising hormone to be released from the pituitary

Question 3

What causes growth hormone release from the anterior pituitary ?

Answer 3

Growth hormone-releasing factor causes growth hormone to be released from the pituitary

Question 4

What causes TSH release ?

Answer 4

Thyrotrophin-releasing hormone causes thyroid-stimulating hormone to be released from the pituitary

Question 5

What is the action of Corticotrophin-releasing factor ?

Answer 5

Corticotrophin-releasing factor causes corticotrophin and B-endorphin to be released from the pituitary

Question 6

What is the action of Melanocyte stimulating hormone ?

Answer 6

Dermal melanin production.

Question 7

What is the action of vasoprsin ?

Answer 7

It controls the water level in the body through its action on the kidney.

Question 8

What is the action of Oxytocin ?

Answer 8

Control uterine contraction

Question 9

T4 is a prohormone ture or false ?

Answer 9

True because it gets converted to T3 in the body.

Question 10

What are the substrates of thyroid hormones ?

Answer 10

Iodine and Tyrosine.

Question 11

What is the half life of T3 ?

Answer 11

a few hours

Question 12

What is the half life of T4 ?

Answer 12

3-4 in hyper or 9-10 days in hypo

Question 13

What is the action and indication of 131-Iodine or radioiodine ?

Answer 13

It is used as a firstline agent for the Tx of hyperthyroidism. It is given as a single dose of 5 to 15mCi and has a1/2 life of 8 days. It has a delayed response of 1 to 2 months. But has strong cytotoxic action due to it emiting gama and beta rays. It can cause hypothyroidism and is not suitable for children and pregnant woman.

Question 14

What is the action of thionamides ?

Answer 14

These are drugs used in hyperthyroidism which act by inhibiting the enzyme thyroperoxide which adds iodide to thyroglobulin to form thyroxine. It also inhibits the release of thyroid hormones from the cell. The clinical response can take 3 to 4 weeks.

Question 15

What are the side effects of thionamides ?

Answer 15

neutropenia and agranulocytosis, rashes, headaches, nausea, jaundice, joint pain

Question 16

What are the commonly used thionamides ?

Answer 16

Carbimazole, methimazole, propylthiouracil ( It also inhibits peripheral conversion of T4 to T3).

Question 17

What is the indication and benefit for large dose iodine ?

Answer 17

• It is indicated as a short term therapy.
  *Temporarily inhibits the release of thyroid hormones
  *Decreases vascularity of the gland
  Symptoms usually subside in 1-2 days

Question 18

What is the indication for propranolol in hyperthyroidism ?

Answer 18

It reduces tremor, palpitations, heat intolerance, nervousness.

Question 19

What is the indication for noradrenergic blocking agent Guanethidine?

Answer 19

It is Given as eye drops for exophthalmos. It acts by relaxing the sympathetically innervated smooth muscle around the eye.

Question 20

What is the indication for Glucocorticoids: Prednisolone, hydrocortisone?

Answer 20

It helps to reduce inflammation of thyroid opthalmopathy and reduces the conversion of T4 to T3.

Question 21

What is the Tx of thyroid Storm ?

Answer 21

A beta blocker (to control the symptoms and signs)

A thionamide to block new hormone synthesis

An iodine solution to block the release of thyroid hormone (>1hr)

Glucocorticoids to reduce T4-to-T3 conversion

Bile acid sequestrants to decrease enterohepatic recycling of thyroid hormones

Question 22

What is the Tx of Hypothyroidism ?

Answer 22

• Iodine (if caused by iodine deficiency)
• Hormone replacement therapy with levothyroxine as first line agent at a dose of 50-100ug/day.
• liothyronine, L-T3 for emergencies as it is short-acting with very short half-life.