Endo (Thyroid and Antithyroid Drugs) Flashcards Preview

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Flashcards in Endo (Thyroid and Antithyroid Drugs) Deck (10):
1

SYNTHESIS AND TRANSPORT OF THYROID HORMONES
Iodide ion is converted to iodine by __________________.
Iodine organification: ____________ residues in thyroglobulin are iodinated to form monoiodotyrosine (MIT) or diiodotyrosine (DIT).
Coupling: Two molecules of DIT combine to form T4. One molecule each of MIT and DIT combine to form T3.
Proteolysis: T4 and T3(more potent) are released from the thyroid and transported in the blood by ____________.

SYNTHESIS AND TRANSPORT OF THYROID HORMONES
Iodide ion is converted to iodine by thyroid peroxidase.
Iodine organification: Tyrosine residues in thyroglobulin are iodinated to form monoiodotyrosine (MIT) or diiodotyrosine (DIT).
Coupling: Two molecules of DIT combine to form T4. One molecule each of MIT and DIT combine to form T3.
Proteolysis: T4 and T3 are released from the thyroid and transported in the blood by thyroxine-binding globulin (TBG).

2

Inhibits TPO. Block iodine organification. Inhibits peripheral conversion of T4 to T3.
DOC for pregnant patients in their first trimester
SE: hepatitis, agranulocytosis
Slow onset of action (3-4 weeks for full effect)

PTU

3

Inhibits TPO. Blocks iodine organification.
DOC for non-pregnant patients
DOC for pregnant patients in their 2nd and 3rd trimesters
If used in first trim: aplasia cutis congenita
SE: agranulocytosis
Slow onset of action (3-4 weeks for full effect)

Methimazole

4

________________
Presentation:
- Acute severe neutropenia often heralded by sore throat or high fever
- Increased susceptibility to infections
Treatment:
- discontinue PTU or methimazole
- administer recombinant _________ to accelerate recovery
- treat with prophylactic broad-spectrum antibiotics

AGRANULOCYTOSIS
Presentation:
- Acute severe neutropenia often heralded by sore throat or high fever
- Increased susceptibility to infections
Treatment:
- discontinue PTU or methimazole
- administer recombinant G-CSF to accelerate recovery
- treat with prophylactic broad-spectrum antibiotics

5

Iodine-____
- emits beta rays causing destruction of thyroid parenchyma
- contraindicated in pregnant women or nursing mothers

Iodine-131
- emits beta rays causing destruction of thyroid parenchyma
- contraindicated in pregnant women or nursing mothers

6

Inhibits iodine organification and hormone release, reduces size and vascularity of thyroid gland
Used for preparation for surgical thryoidectomy, radiation prophylaxis, hyperthyroidism, thyroid storm
Prenatal exposure causes fetal goiter

Potassium iodide
SimD: Lugol's solution

7

Wolf-Chaikoff effect vs. Jod-Basedow phenomenon
Ingestion of iodine causes hypothyroidism: ________
Ingestion of iodine causes hyperthyroidism: ________

Wolf-Chaikoff effect (Wolf-hypo effect)
Jod-Basedow phenomenon (Hyperbasedow)

8

What antithyroid drugs inhibit peripheral conversion of T4 to T3?

Propylthiouracil
Propranolol
Hydrocortisone

9

In treating thyroid storm, always administer ________ first before iodides.
Propranolol
Hydrocortisone

In treating thyroid storm, always administer PTU first before iodides.
Propranolol
Hydrocortisone

10

What drugs can cause drug-induced hyperthyroidism? (3)

CAM
Clofibrate
Amiodarone
Methadone

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