[MCQ] Disorders of the Thyroid Gland- Part 3

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Disorders of the Thyroid Gland- Part 3

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Question 1

Which of the following plays a role in feedback control of the thyroid axis in hypothalamus and pituitary ?

A	TRα1
B	TRβ1
C	TRα2
D	TRβ2

Question 1 Explanation:

The TR-beta2 isoform, which has a unique amino terminus, is selectively expressed in the hypothalamus and pituitary, where it plays a role in feedback control of the thyroid axis.

Question 2

Which of the following prevents thyroid hormone binding ?

A	TRα1
B	TRβ1
C	TRα2
D	TRβ2

Question 2 Explanation:

TR - 2 isoform contains a unique carboxy terminus that precludes thyroid hormone binding

Question 3

Thyroid hormone receptor (TR) binds to which of the following in the promoter region of target genes ?

A	Thyroid hormone reccruiting elements
B	Thyroid hormone receptor elements
C	Thyroid hormone response elements
D	Thyroid hormone reacting elements

Question 3 Explanation:

In nucleus, thyroid hormone receptor (TR) & retinoid X receptor (RXR) form heterodimers that bind

Question 4

Serum T4 has a plasma half-life of ?

A	1 day
B	3 days
C	7 days
D	10 days

Question 5

Serum T3 has a plasma half-life of about ?

A	1 day
B	3 days
C	7 days
D	10 days

Question 6

What fraction of circulating T3 comes directly from thyroid gland ?

A	10 %
B	20 %
C	30 %
D	40 %

Question 7

What fraction of circulating T4 comes directly from thyroid gland ?

A	25 %
B	50 %
C	75 %
D	100 %

Question 8

Normally, secretion ratio from thyroid gland of T3 & T4 is ?

A	1 : 10
B	1 : 20
C	1 : 30
D	1 : 40

Question 9

Which of the following statements about resistance to thyroid hormone (RTH) is false ?

A	Autosomal dominant disorder
B	Due to mutation in TR receptor gene
C	Elevated free thyroid hormone levels
D	Presents as hypothyroidism

Question 9 Explanation:

Resistance to thyroid hormone (RTH) is an autosomal dominant disorder characterized by elevated thyroid hormone levels & inappropriately normal or elevated TSH. Individuals with RTH do not exhibit signs & symptoms of hypothyroidism because hormone resistance is partial and is compensated by increased levels of thyroid hormone. RTH is caused by mutations in the R receptor gene.

Question 10

Which of the following statements about resistance to thyroid hormone (RTH) is false ?

A	Goiter
B	Tachycardia
C	Impaired metabolic responses to thyroid hormone
D	Treated with thyroid replacement drugs

Question 10 Explanation:

Clinical features of RTH include goiter, attention deficit disorder, mild reduction in IQ, delayed skeletal maturation, tachycardia & impaired metabolic responses to thyroid hormone. Mostly no treatment is indicated, rather inappropriate treatment of mistaken hyperthyroidism should be avoided.

Question 11

Pemberton’s sign is elicited by ?

A	Act of swallowing
B	Raising of arms
C	Extrusion of tongue
D	All of the above

Question 11 Explanation:

Large retrosternal goiters can cause venous distention over the neck and difficulty breathing, especially when the arms are raised (Pemberton’s sign). With any central mass above the thyroid, the tongue should be extended, as thyroglossal cysts then move upward

Question 12

Free T3 index is calculated by ?

A	Thyroid hormone binding ratio (THBR) x Total T3
B	Thyroid hormone binding ratio (THBR) / Total T3
C	Thyroid hormone binding ratio (THBR) x Free T3
D	Thyroid hormone binding ratio (THBR) / Free T3

Question 12 Explanation:

The product of THBR and total T3 or T4 provides the free T3 or T4 index. In effect, the index corrects for anomalous total hormone values caused by abnormalities in hormone-protein binding

Question 13

TBG is increased due to all except ?

A	Pregnancy
B	Hormone replacement therapy
C	Nephrotic syndrome
D	Tamoxifen

Question 13 Explanation:

Total thyroid hormone levels are elevated when TBG is increased due to estrogens (pregnancy, oral contraceptives, hormone therapy, tamoxifen). TBG is reduced by androgens & in nephrotic syndrome.

Question 14

In pregnancy, circulating free T4, free T3 and TSH are ?

A	Normal
B	Increased
C	Decreased
D	Any of the above

Question 15

TSH levels are elevated in all except ?

A	Hypothyroidism
B	Thyroid hormone resistance
C	First trimester of pregnancy
D	TSH-secreting pituitary tumor

Question 16

TSH levels are suppressed in ?

A	Thyrotoxicosis
B	First trimester of pregnancy
C	Insulin
D	Dopamine

Question 16 Explanation:

Elevated TSH levels occur in hypothyroidism most commonly, and also in TSH-secreting pituitary tumor, thyroid hormone resistance & assay artifact. Suppressed TSH level (<0.1 mU/L) indicates thyrotoxicosis but are also seen during first trimester of pregnancy (due to hCG secretion), after treatment of hyperthyroidism & in response to high doses of glucocorticoids or dopamine

Question 17

Which of the following radioisotopes of iodine is used for thyroid imaging ?

A	123I
B	125I
C	131I
D	All of the above

Question 17 Explanation:

Thyroid gland selectively transports radioisotopes of iodine (123I, 125I, 131I) and 99mTc pertechnetate, allowing thyroid imaging & quantitation of radioactive tracer fractional uptake.

Question 18

What frequency of transducer is best for thyroid ultrasonography ?

A	2.5 MHz
B	5 MHz
C	7.5 MHz
D	10 MHz

Question 18 Explanation:

A 10-MHz ultrasound probe can detect thyroid nodules and cysts >3 mm.

Question 19

Neonatal hypothyroidism is most frequently due to ?

A	Thyroid gland dysgenesis
B	Inborn errors of thyroid hormone synthesis
C	TSH-R antibody-mediated
D	Idiopathic

Question 19 Explanation:

Neonatal hypothyroidism is due to thyroid gland dysgenesis in 80 - 85%, to inborn errors of thyroid hormone synthesis in 10 - 15% & is TSH-R antibody-mediated in 5% of affected newborns.

Question 20

Which of the following is the most common symptom of hypothyroidism ?

A	Dry skin
B	Hair loss
C	Constipation
D	Weight gain with poor appetite

Question 21

Which of the following is the most common sign of hypothyroidism ?

A	Bradycardia
B	Diffuse alopecia
C	Dry coarse skin
D	Peripheral oedema

Question 22

Symptoms of hypothyroidism become more readily apparent at TSH levels of ?

A	> 7 mU/L
B	> 8 mU/L
C	> 9 mU/L
D	> 10 mU/L

Question 22 Explanation:

Symptoms of hypothyroidism become more readily apparent at when TSH is >10 mU/L.

Question 23

Which of the following is false about Hashimoto’s thyroiditis ?

A	Lymphocytic infiltration
B	Atrophy of thyroid follicles
C	No fibrosis
D	May progress to atrophic thyroiditis

Question 23 Explanation:

In Hashimoto’s thyroiditis, there is a marked lymphocytic infiltration of thyroid with germinal center formation, atrophy of thyroid follicles accompanied by oxyphil metaplasia, absence of colloid & mild to moderate fibrosis

Question 24

Lymphocytic infiltrate in autoimmune hypothyroidism is composed of ?

A	Activated CD4+ T cells
B	Activated CD8+ T cells
C	B cells
D	All of the above

Question 24 Explanation:

Thyroid lymphocytic infiltrate in autoimmune hypothyroidism is composed of activated CD4+, CD8+ T cells and B cells. Thyroid cell destruction is primarily mediated by CD8+ cytotoxic T cells.

Question 25

Which of the following is false about Hashimoto’s encephalopathy ?

A	Grand Mal seizure
B	Slow-wave activity on EEG
C	Steroid-responsive
D	May occur in autoimmune thyroiditis without hypothyroidism

Question 25 Explanation:

Hashimoto’s encephalopathy is a steroid-responsive syndrome associated with TPO antibodies, myoclonus & slow-wave activity on EEG.

Question 26

Daily replacement dose of levothyroxine is usually ?

A	1.6 μg/kg body weight
B	1.8 μg/kg body weight
C	2.0 μg/kg body weight
D	2.2 μg/kg body weight

Question 26 Explanation:

If there is no residual thyroid function, daily replacement dose of levothyroxine is usually 1.6 μg/ kg body weight (typically 100 - 150 μg).

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See all quizzes of Disorders of the Thyroid Gland at here:

Disorders of the Thyroid Gland- Part 1| Disorders of the Thyroid Gland- Part2| Disorders of the Thyroid Gland- Part 3| Disorders of the Thyroid Gland- Part 4| Disorders of the Thyroid Gland- Part 5

1.Which of the following plays a role in feedback control of the
thyroid axis in hypothalamus and pituitary ?
A. TR1
B. TR1
C. TR2
D. TR2

2 Which of the following prevents thyroid hormone binding ?
A. TR1
B. TR1
C. TR2
D. TR2

3 Thyroid hormone receptor (TR) binds to which of the following
in the promoter region of target genes ?
A. Thyroid hormone reccruiting elements
B. Thyroid hormone receptor elements
C. Thyroid hormone response elements
D. Thyroid hormone reacting elements

4 Serum T4 has a plasma half-life of ?
A. 1 day
B. 3 days
C. 7 days
D. 10 days
5 Serum T3 has a plasma half-life of about ?
A. 1 day
B. 3 days
C. 7 days
D. 10 days
6 What fraction of circulating T3 comes directly from thyroid
gland ?

A. 10 %
B. 20 %
C. 30 %
D. 40 %
7 What fraction of circulating T4 comes directly from thyroid
gland ?
A. 25 %
B. 50 %
C. 75 %
D. 100 %
8 Normally, secretion ratio from thyroid gland of T3 & T4 is ?
A. 1 : 10
B. 1 : 20
C. 1 : 30
D. 1 : 40

9 Which of the following statements about resistance to thyroid
hormone (RTH) is false ?
A. Autosomal dominant disorder
B. Due to mutation in TR receptor gene
C. Elevated free thyroid hormone levels
D. Presents as hypothyroidism

10 Which of the following statements about resistance to thyroid
hormone (RTH) is false ?
A. Goiter
B. Tachycardia
C. Impaired metabolic responses to thyroid hormone
D. Treated with thyroid replacement drugs

11 Pemberton’s sign is elicited by ?
A. Act of swallowing
B. Raising of arms
C. Extrusion of tongue
D. All of the above

12 Free T3 index is calculated by ?
A. Thyroid hormone binding ratio (THBR) x Total T3
B. Thyroid hormone binding ratio (THBR) / Total T3
C. Thyroid hormone binding ratio (THBR) x Free T3
D. Thyroid hormone binding ratio (THBR) / Free T3

13 TBG is increased due to all except ?
A. Pregnancy
B. Hormone replacement therapy
C. Nephrotic syndrome
D. Tamoxifen

14 In pregnancy, circulating free T4, free T3 and TSH are ?
A. Normal
B. Increased
C. Decreased
D. Any of the above

15 TSH levels are elevated in all except ?
A. Hypothyroidism
B. Thyroid hormone resistance
C. First trimester of pregnancy
D. TSH-secreting pituitary tumor
16 TSH levels are suppressed in ?
A. Thyrotoxicosis
B. First trimester of pregnancy
C. Insulin
D. Dopamine

17 Which of the following radioisotopes of iodine is used for thyroid
imaging ?A. 123I
B. 125I
C. 131I
D. All of the above

18 What frequency of transducer is best for thyroid ultrasonography ?
A. 2.5 MHz
B. 5 MHz
C. 7.5 MHz
D. 10 MHz

19 Neonatal hypothyroidism is most frequently due to ?
A. Thyroid gland dysgenesis
B. Inborn errors of thyroid hormone synthesis
C. TSH-R antibody-mediated
D. Idiopathic

20 Which of the following is the most common symptom of
hypothyroidism ?
A. Dry skin
B. Hair loss
C. Constipation
D. Weight gain with poor appetite
21 Which of the following is the most common sign of
hypothyroidism ?
A. Bradycardia

B. Diffuse alopecia
C. Dry coarse skin
D. Peripheral oedema
22 Symptoms of hypothyroidism become more readily apparent at
TSH levels of ?
A. > 7 mU/L
B. > 8 mU/L
C. > 9 mU/L
D. > 10 mU/L

23 Which of the following is false about Hashimoto’s thyroiditis ?
A. Lymphocytic infiltration
B. Atrophy of thyroid follicles
C. No fibrosis
D. May progress to atrophic thyroiditis

24 Lymphocytic infiltrate in autoimmune hypothyroidism is
composed of ?
A. Activated CD4+ T cells
B. Activated CD8+ T cells
C. B cells
D. All of the above

25 Which of the following is false about Hashimoto’s
encephalopathy ?
A. Grand Mal seizure
B. Slow-wave activity on EEG
C. Steroid-responsive
D. May occur in autoimmune thyroiditis without hypothyroidism

26 Daily replacement dose of levothyroxine is usually ?
Harrison’s 18th Ed. 2921
A. 1.6 μg/kg body weight
B. 1.8 μg/kg body weight
C. 2.0 μg/kg body weight
D. 2.2 μg/kg body weight

[MCQ] Disorders of the Thyroid Gland- Part 3

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Disorders of the Thyroid Gland- Part 3

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