Ch 19

Question 1

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

Answer 1

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

Question 2

Which of the following is NOT essential for normal biosynthesis of thyroid hormones?
A. Iodine
B. Ferritin
C. Thyroglobulin 
D. Protein synthesis 
E. TSH

Answer 2

B. Ferritin

Question 3

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

Answer 3

E. Secondary active transport

Question 4

The metabolic rate is least affected by an increase in the plasma level of
A. TSH 
B. TRH 
C. TBG 
D. Free T4 
E. Free T3

Answer 4

C. TBG

Question 5

In which of the following conditions is it most likely that the TSH response to TRH will be reduced?
A. Hypothyroidism due to tissue resistance to thyroid hormone
B. Hypothyroidism due to disease destroying the thyroid gland
C. Hyperthyroidism due to circulating antithyroid antibodies with TSH activity
D. Hyperthyroidism due to diffuse hyperplasia of thyrotropes of the anterior pituitary
E. Iodine deficiency

Answer 5

C. Hyperthyroidism due to circulating antithyroid antibodies

with TSH activity

Question 6

Hypothyroidism due to disease of the thyroid gland is associated with increased plasma levels of
A. Cholesterol 
B. Albumin 
C. RT3
D. Iodide
E. TBG

Answer 6

A. Cholesterol

Question 7

A young woman has puffy skin and a hoarse voice. Her plasma TSH concentration is low but increases markedly when she is given TRH. She probably has
A. hyperthyroidism due to a thyroid tumor.
B. hypothyroidism due to a primary abnormality in the thyroid
gland.
C. hypothyroidism due to a primary abnormality in the
pituitary gland.
D. hypothyroidism due to a primary abnormality in
the hypothalamus.
E. hyperthyroidism due to a primary abnormality
in the hypothalamus.

Answer 7

D. hypothyroidism due to a primary abnormality in

the hypothalamus.

Question 8

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

Answer 8

A. D1 thyroid deiodinase

Question 9

Which of the following would be least affected by injections of TSH?
A. Thyroidal uptake of iodine
B. Synthesis of thyroglobulin
C. Cyclic adenosine monophosphate (cAMP) in thyroid cells
D. Cyclic guanosine monophosphate (cGMP) in thyroid cells
E. Size of the thyroid

Answer 9

D. Cyclic guanosine monophosphate (cGMP) in thyroid cells

Question 10

Thyroid hormone receptors bind to DNA in which of the following forms?
A. A heterodimer with the prolactin receptor
B. A heterodimer with the growth hormone receptor
C. A heterodimer with the retinoid X receptor
D. A heterodimer with the insulin receptor
E. A heterodimer with the progesterone receptor

Answer 10

C. A heterodimer with the retinoid X receptor