Thyroid Hormones MCQ Quiz | Endocrine Biochemistry

Welcome to the Endocrine Biochemistry quiz on Thyroid Hormones, specifically designed for MBBS students. This comprehensive quiz features 25 multiple-choice questions covering the synthesis, regulation, transport, and mechanism of action of thyroid hormones. You will explore key concepts from iodide trapping and organification to the physiological effects on basal metabolic rate and nervous system development. This assessment also touches upon important clinical correlations, including the biochemical basis of hypothyroidism and hyperthyroidism, and the interpretation of thyroid function tests. After submitting your answers, you will receive your score, and the correct answers will be highlighted for your review. For offline study, you can download all the questions and their correct answers as a PDF file.

1. Which transporter is responsible for the active uptake of iodide into follicular cells of the thyroid gland?

2. The process of incorporating oxidized iodine into tyrosine residues of thyroglobulin is known as:

3. Which enzyme is crucial for both the oxidation of iodide and the coupling of iodotyrosine residues to form T3 and T4?

4. Which of the following is the most biologically active thyroid hormone?

5. The synthesis and secretion of thyroid hormones are primarily regulated by negative feedback of T3 and T4 on the:

6. Which protein has the highest affinity for binding and transporting T4 in the blood?

7. The conversion of T4 to the more active T3 in peripheral tissues is catalyzed by which family of enzymes?

8. Propylthiouracil (PTU) is a drug used to treat hyperthyroidism. Its primary mechanism of action is inhibiting:

9. Thyroid hormones exert their effects primarily by binding to:

10. What is the primary effect of thyroid hormones on the Basal Metabolic Rate (BMR)?

11. The formation of Reverse T3 (rT3) from T4 is a mechanism for:

12. Myxedema, characterized by the accumulation of glycosaminoglycans in the interstitial space, is a clinical sign of severe:

13. Graves’ disease is an autoimmune disorder where autoantibodies stimulate which receptor, leading to hyperthyroidism?

14. Where are the newly synthesized thyroid hormones stored before being secreted into the bloodstream?

15. Which type of deiodinase is primarily responsible for generating most of the circulating T3?

16. What hormone is released from the hypothalamus to stimulate the anterior pituitary to release TSH?

17. A patient presents with primary hypothyroidism due to Hashimoto’s thyroiditis. What pattern of Thyroid Function Tests (TFTs) would be expected?

18. In a patient with primary hyperthyroidism (e.g., Graves’ disease), the expected TFT results would be:

19. The calorigenic effect of thyroid hormones is largely due to the increased synthesis and activity of:

20. Thyroid hormones are critically important for the normal development of which system in the fetus and neonate?

21. The administration of a large dose of iodine leads to a temporary inhibition of thyroid hormone synthesis. This phenomenon is known as the:

22. Pendred syndrome is an autosomal recessive disorder characterized by goiter and sensorineural deafness, caused by a mutation in the gene for:

23. The coupling of one molecule of monoiodotyrosine (MIT) and one molecule of diiodotyrosine (DIT) within the thyroglobulin molecule forms:

24. The release of T3 and T4 from the follicular cell into the bloodstream involves which cellular process?

25. Why does T4 have a significantly longer plasma half-life (around 7 days) compared to T3 (around 1 day)?