Medical Pharmacology: Thyroid Pharmacology Practice Questions

Medical Pharmacology: Thyroid Pharmacology Practice Questions

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- Haggstrom: Public Domain
- https://en.wikipedia.org/wiki/File:Thyroid_system.svg

Click on the correct answer.

Thyroxine (T₄):
1. Narrow therapeutic index where the therapeutic index is the dose range in which an agent is efficacious with the absence of unacceptable adverse effects.
2. Use of the proper dosage is necessary to avoid iatrogenic thyrotoxicosis.
3. Both
4. Neither
Thyroxine: optimal absorption in the duodenum and ileum.
1. True
2. False
L-thyroxine versus triiodothyronine (T₃) absorption:
1. Thyroxine: about 70%-80% oral bioavailability
2. T₃ absorption: about 95%
3. Both
4. Neither
T₄ and T₃ absorption:
1. Somewhat enhanced with mild hypothyroidism
2. Substantially elevated in patients with severe myxedema with ileus.
3. Both
4. Neither
In hyperthyroid patients:
1. T₄ and T₃ metabolic clearance is elevated.
2. T₄ and T₃ half-lives are reduced.
3. Both
4. Neither
In the context of limited intestinal absorption or if the patient generally is not able to take oral medication, levothyroxine (L-thyroxine) may be given intravenously.
1. True
2. False
Following oral dosing, L-thyroxine serum levels peak at about 2-4 hours.
1. True
2. Poles
Treating clinical hypothyroidism:
1. L-thyroxine doses adjusted based on TSH levels.
2. TSH responses tend to be rapid with relevant clinical effects evident within the first 24 hours.
3. Both
4. Neither
Following L-thyroxine treatment, some patients (10%-15%) will continue to exhibit symptoms even though they are euthyroid (normal thyroid levels).
1. True
2. False
The principal complication associated with thyroxine treatment is iatrogenic thyrotoxicosis.
1. True
2. False

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Source Material:
- Koenig RJ Brent GA Chapter 47 Thyroid and Antithyroid Drugs In Goodman & Gilman's The Pharmacological Basis of Therapeutics (Brunton LL Knollman BC eds) McGraw Hill LLC (2023).
- Jameson JL Mandel SJ Weetman AP Ch 383 Hypothyroidism in Harrison's Principles of Internal Medicine, 21e McGraw Hill 2022.
- Jameson JL Mandel SJ Weetman AP Ch 384 Hyperthyroidism and Other Causes of Thyrotoxicosis in Harrison's Principles of Internal Medicine, 21e 2022.
- Jameson JL Mandel SJ Weetman AP Ch 385 Thyroid Nodular Disease and Thyroid Cancer in Harrison's Principles of Internal Medicine, 21e 2022.
- Bong BJ Thyroid Drugs & Anti-thyroid Drugs Ch 38 in Katzung's Basic & Clinical Pharmacology (Vanderah TW, ed) 16e McGraw Hill 2023.
- Jonklaas J Cooper DS Ch 213 Thyroid in Goldman-Cecil Medicine E-Book (Goldman L Schafer AI, eds) 26e Elsevier 2020.
- Ritter JM Flower R Henderson G Loke YK MacEwan D Robinson E Fullerton J Chapter 53 Antiviral Drugs Rand & Dale's Pharmacology 10e Elsevier 2024.
- Hollenberg A Chin WW Pharmacology of the Thyroid Gland Chapter 28 in Principles of Pharmacology: The Pathophysiologic Basis of Drug Therapy. (Golan DE Armstrong EJ Armstrong AW, eds) 4e 2017.