Thyroid Function Test

Question 1

most important in control of thyroid hormone levels

Answer 1

negative feedback loop

Question 2

state of having normal thyroid gland function

Answer 2

euthyroid

Question 3

how many % of gut absorbed inorganic iodide is trapped by the thyroid gland

Answer 3

20-40%

Question 4

produced by basophil cells of the
anterior pitutary and principal stimulator for iodide transport into the thyroid

Answer 4

Thyrotropin or TSH

Question 5

This may lead to depression of the thyroid’s iodine-trapping mechanism.

Answer 5

chronic excess of iodide

Question 6

formed by the rough endoplasmic
reticulum of the follicular cells and is secreted into the follicular lumen

Answer 6

thyroglobulin

Question 7

release of thyroid hormone is controlled by?

Answer 7

TSH

Question 8

Iodinated thyroglobulin near the cell-colloid interface is hydrolyzed by these substances to release MIT, DIT, T3
and T4 into the cell

Answer 8

proteases and peptidases

Question 9

True or False. The binding affinity for T4 is lower in the dog than the humans.

Answer 9

True

Question 10

When T4 is released from the thyroid,
approximately how many % remains in the plasma?

Answer 10

40 percent

Question 11

an expensive test for Grave’s disease

Answer 11

Serum thyroid stimulating immunoglobulin (TSI) or TSHR-Ab

Question 12

marker for recurrent thyroid cancer, and also differentiate graves disease from factitious thyrotoxicosis

Answer 12

Serum thyroglobulin

Question 13

Characteristics of Antithyroid peroxidase antibodies (TPO)

Answer 13

• organ specific and sensitive
• predict overt hypothyroidism

Question 14

it is inactive and helpful to exclude central hypothyroidism

Answer 14

Reverse T3

Question 15

useful in distinguishing t3 toxicosis from subclinical thyrotoxicosis

Answer 15

fT3

Question 16

preferred test with TSH

Answer 16

FT4 assay

Question 17

In dogs with normal total T4 concentrations the average calculated T3 not bound by T3 AA

Answer 17

147.2 +/- 144.4 ng/dl

Question 18

dogs with low total T4 the value of average calculated T3 not bound by T3 AA

Answer 18

15.7 +/- 26.3 ng/dl

Question 19

normal canine range of total T4 concentrations the average calculated T3 not bound by T3 AA

Answer 19

45-150 ng/dl

Question 20

acts as an acceptor also involved in synthesis and later release of T4 and T3

Answer 20

Thyroglobulin

Question 21

the biologically active form of T4 that can enter most cells of the body

Answer 21

Ft4

Question 22

True or False. T4 and T3 are excreted in bile and urine.

Answer 22

True.

Question 23

standard screening test for hypothyroidism in dogs

Answer 23

Basal tT4

Question 24

an inheritable autoimmune disorder in many dog breeds, common cause of thyroid gland destruction and primary hypothyroidism in dogs at least 50% of cases

Answer 24

Lymphocytic thyroiditis

Question 25

disease outside of thyroid hormonal system creates hypothyroxemia

Answer 25

Sick euthyroidism

Question 26

Increase/Decrease. Effects of neoplastic, inflammatory, metabolic, endocrine disorders on tT4

Answer 26

Decreased.

Question 27

It helps differentiate nonthyroidal illness from hypothyroidism when tT4 is decreased in dogs

Answer 27

Assessment of TSH and fT4

Question 28

Diet contents that may produce lower tT4 in horses

Answer 28

protein, energy, copper, zinc

Question 29

True or False. fT4 does not always mirror tT4

Answer 29

True.

Question 30

Concurrently finding decreased tT4 and increased fT4 in cats, suggests?

Answer 30

Presence of sick euthyroid state.

Question 31

Increase or Decrease. TSH levels in dogs with primary hypothyroidism.

Answer 31

Increased.

Question 32

Poor or inadequate response to TSH stimulation was the gold standard for establishing this condition

Answer 32

thyroid hypoplasia (hypothyroidism)

Question 33

assess the ability of the thyroid gland to produce T4 after being stimulated by TSH

Answer 33

TSH response test

Question 34

indirectly assess thyroid function by causing the release of TSH that stimulates release of T4

Answer 34

TRH response test

Question 35

TRH response test in not approved in these species

Answer 35

horses

Question 36

TRH response test is not needed to diagnose hyperthyroidism in these species

Answer 36

Cats

Question 37

a useful screening test for diagnosing hypothyroidism in dogs

Answer 37

Total T4 (Thyroxine) measurement

Question 38

useful for diagnosis of true hypothyroidism and differentiating it from euthyroid sick condition

Answer 38

fT4 measurement