Thyroid drugs - Staudinger

Question 1

• levothyroxine (T4)
• liothyronine (T3)
• liotrix (4:1 ratio of T4:T3)
• thyroid dessicated

Answer 1

thyroid agents

Question 2

• radioactive iodine
• potassium iodide
• methimazole
• PTU

Answer 2

anti-thyroid agents

Question 3

what drug is widely used to reduce heart rate and tremor during a thyroid storm?

Answer 3

propranolol

• inhibits conversion of T4 to T3, which occurs in peripheral tissues
• may help reverse reduced systemic vascular resistance

Question 4

what drug can cause type II thyrotoxicosis?

Answer 4

amiodarone
- occurs from actual thyroid tissue destruction

NOTE: pts started on amiodarone need baseline measures of TSH, free T3 and T4 (repeat every6-12 months)

Question 5

commonly prescribed medication for arrhythmia

- both atrial and ventricular arrhythmias

Answer 5

amiodarone

Question 6

what is the dosage of iodine in each 200mg tablet of amiodarone?

Answer 6

74.4mg of iodine, with 7.4mg (10%) per day being released as free iodine

Question 7

what is the daily recommended iodine intake for adults?

Answer 7

0.15mg

Question 8

what is the anti-thyroid drug used to treat hyperthyroidism?

Answer 8

methimazole

- thioamide group of medications - blocks iodide organification

Question 9

• PTU
• methimazole
• carbimazole

Answer 9

thioamide group of medications

Question 10

what medication inhibits the enzyme thyroperoxidase?

Answer 10

methimazole

- thioperoxidase catalyzes a necessary step in the synthesis of T3 and T4

Question 11

• stable form of iodine
• blocks iodine uptake
• used as treatment for hyperthyroidism
• used as treatment for iodine deficiency
• used along with anti-thyroid medication to prepare thyroid gland for surgical removal

Answer 11

potassium iodide

Question 12

• used to protect the thyroid from radiation exposure (shrinks thyroid gland, decreasing TH production)
• does not effect heart rate
• does not produce irregular heartbeat

Answer 12

potassium iodide

Question 13

• patients with Graves disease
• pt with toxic multinodular goiter (intelerant of methimazole, surgery or radioactive iodine therapy is not appropriate tx option)
• used to relieve sx of hyperthyroidism
• used for prep of thyroidectomy
• used in radioactive iodine therapy in pts who are intolerant of methimazole

Answer 13

propothiouracil (PTU)

Question 14

inhibits synthesis of thyroid hormones in hyperthyroidism

• inhibits conversion of thyroxine to T3 in peripheral tissues
• does not inactivate pre-existing T4 and T3
• does not interfere with effectiveness of thyroid hormones given by mouth or by injection
• may be an effective treatment for thyroid storm

Answer 14

PTU

Question 15

• produced by the pituitary gland, in response to TRH from hypothalamus
• promotes growth of the thyroid gland
• stimulates production of thyroid hormones

Answer 15

TSH

- excessive thyroid hormones -> pituitary gland stops producing TSH

Question 16

what is the most sensitive screening test for hyperthyroidism and primary hypothyroidism?

Answer 16

TSH

- if within normal limits, these diagnoses can be excluded

Question 17

• used to treat hormone deficiency
• manufactured form of thyroid hormone -> T4
• converted to T3
• maximum effect can take up to six weeks

Answer 17

levothyroxine (L-thyroxine)

Question 18

what are the side effects from excessive dosing of L-thyroxine

Answer 18

• weight loss
• heat intolerance
• sweating
• anxiety
• trouble sleeping
• tremor
• tachycardia

Question 19

what is the highlighted drug that impairs levothyroxine absorption?

Answer 19

cholestramine

Question 20

what therapy for thyroid cancer contraindicated in pregnancy women?

Answer 20

radioactive iodine

• thyroid gland absorbs iodine
• radiation destroys the thyroid gland

Question 21

beta blocker with less cerebral effects than propranolol

• membrane-stabilizing action
• inhibits T4 to T3 conversion
• indicated in Graves disease and thyroid storm

Answer 21

atenolol

Question 22

which beta blocker is the most widely studied and used in thyrotoxicosis?

Answer 22

propranolol

Question 23

• inhibits thyroid hormone production
• competitive inhibitor of iodide uptake by thyroid gland
• blocks sodium-iodide symporter (NIS)
• no effect on iodination process

Answer 23

perchlorate-blocking agent