Thyroid

Question 1

Liothyronine sodium

Answer 1

L-triiodothyronine- T3. Potent, short-acting T3. Used for short-term suppression of TSH.

Question 2

Liothyronine sodium: safety

Answer 2

More difficult to monitor than T4, increased risk of cardiotoxicity

Question 3

Levothyroid sodium

Answer 3

L-thyroxin (T4). Drug of choice for replacement in hypothyroidism. T4 is converted to T3 by deiodinase 1. Once daily dosing.

Question 4

Levothyroid sodium: safety

Answer 4

SE: Angina, palpitations.
Warning: dose adjust for elderly and pregnant patients.
Rifampin increases T4 clearance, cholestyramine decreases absorption

Question 5

Propylthiouracil

Answer 5

Target: TPO (thyroidal peroxidase) prevents hormone synthesis AND peripheral conversion of T4 to T3. Used to treat thyrotoxicosis, thyroid storm.

Question 6

Propylthiouracil: safety

Answer 6

SE: rash, joint pain, agranulocytosis

hepatotoxic (worse than MMI).
Preferred antithyroid medication in pregnant and nursing patients.

Question 7

Methimazole

Answer 7

anti-thyroid drug used to treat thyrotoxicosis. Prevents hormone synthesis by blocking TPO (thyroidal peroxidase).

Question 8

Methimazole: safety

Answer 8

Less hepatotoxic than PPT. MMI is preferred in pregnancy. Longer half-life than PPT.

Can cause congenital scalp defects.

Question 9

Iodide

Answer 9

used in hyperthyroidism before thioamides were created. Combined w/ PTU and beta blocker in tx of thyroid storm.

Question 10

Iodide: safety

Answer 10

actinform rash, swollen saliva glands, mucous membrane ulcerations.
CI in pregnancy (fetal goiter)

Question 11

I-131 - use and safety

Answer 11

Tx of thyrotoxicosis. CI in pregnancy and children. Will eventually cause hypothyroidism.

Question 12

Pre-operative treatment for thyroidectomy

Answer 12

Give thioamide (PPT or MMI) until euthyroid. KI for 10 days prior to surgery to reduce thyroid size and vascularity.