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Chapter 20. The Thyroid Gland

A 40-year-old woman comes to her primary care clinician complaining of nervousness and an unexplained weight loss of 20 pounds over the past 3 months despite her impression that she is eating all the time. On physical examination, her eyes are found to be protruding, her skin is moist and warm, and her fingers have a slight tremor. Compared to a healthy individual, a biopsy of her thyroid gland would most likely reveal which of the following:

A. Decreased numbers of reabsorption lacunae

B. Decreased evidence of endocytosis

C. A decrease in the cross-sectional area occupied by colloid

D. Increased levels of NIS in the basolateral membrane of thyrocytes

E. Decreased evidence of lysosomal activity

Which of the following is not essential for normal biosynthesis of thyroid hormones?

A. Iodine

B. Ferritin

C. Thyroglobulin

D. Protein synthesis


The enzyme primarily responsible for the conversion of T4 to T3 in the periphery is

A. D1 thyroid deiodinase.

B. D2 thyroid deiodinase.

C. D3 thyroid deiodinase.

D. thyroid peroxidase.

E. None of the above.

Increasing intracellular I due to the action of NIS is an example of

A. endocytosis.

B. passive diffusion.

C. Na+ and K+ cotransport.

D. primary active transport.

E. secondary active transport.

The metabolic rate is least affected by an increase in the plasma level of




D. Free T4.

E. Free T3.

In which of the following conditions is it most likely that the TSH response to TRH will be reduced?


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