Question 1

Given the following characteristics, which disease state is most likely?
TSH - increased
FT₄ - increased
FT₃ - increased
T₃RU - decreased
TSI - negative
TPO-ab - unlikely to be positive
Thyroid scan uptake - increased

A)Graves' disease
B)autoimmune thyroiditis
C)secondary hyperthyroidism
D)primary hypothyroidism

secondary hyperthyroidism

Accepted Answer

The typical thyroid function test results will have the following characteristics in secondary hyperthyroidism: TSH, increased; fT₄, increased; fT₃, increased; T₃RU, decreased; TSI, negative; TPO-ab, unlikely to be positive; thyroid scan uptake, increased.

Question 2

What tests are used as part of newborn screening programs to identify congenital hypothyroidism?&#10;A)T&#8323; and/or TSH&#10;B)T&#8324; and/or TSH&#10;C)T&#8323; and/or T&#8324;&#10;D)fT&#8323; and/or T&#8324;

Accepted Answer

Congenital hypothyroidism occurs in approximately 1:4000 newborns and is one of the most common, treatable causes of mental retardation.Most newborns with congenital hypothyroidism have few or no clinical manifestations of thyroid deficiency, and the majority of cases are sporadic.For these reasons, newborn screening programs in which T₄ and/or TSH are measured in heel-prick blood specimens were developed in the mid-1970s to detect this condition as early as possible.

Question 3

Thyroid hormones exert influence in most areas of the body.How do thyroid hormones influence the heart?&#10;A)They affect cardiac gene expression.&#10;B)They influence the sensitivity of the heart to the sympathetic nervous system.&#10;C)They cause peripheral hemodynamic alterations that influence cardiac function.&#10;D)All of the above

Accepted Answer

In the heart, thyroid hormones affect cardiac gene expression-for example, stimulating myosin a-heavy chain synthesis and depressing myosin b-heavy chain synthesis.They influence the sensitivity of the heart to the sympathetic nervous system by stimulating synthesis of b₁-adrenergic receptors.Thyroid hormones also cause peripheral hemodynamic alterations that influence cardiac function.

Question 4

After treatment with medication or radioactive iodine is initiated for hyperthyroidism, disease activity is best initially monitored with ______, because ______ will take several weeks or more to return to the reference interval.

A)TSH, T₄ and T3
B)TSH, fT₃ and fT₄
C)fT₃ and fT₄, TSH
D)serum iodine, TSH

Accepted Answer

After treatment with medication or radioactive iodine is initiated for hyperthyroidism, disease activity is best initially monitored with ______, because ______ will take several weeks or more to return to the reference interval.

A)TSH, T₄ and T3
B)TSH, fT₃ and fT₄
C)fT₃ and fT₄, TSH
D)serum iodine, TSH

Question 5

Given the following characteristics, which disease state is most likely?
TSH - increased
FT₄ - increased
FT₃ - increased
T₃RU - decreased
TSI - negative
TPO-ab - unlikely to be positive
Thyroid scan uptake - increased

A)Graves' disease
B)autoimmune thyroiditis
C)secondary hyperthyroidism
D)primary hypothyroidism

secondary hyperthyroidism

Accepted Answer

The typical thyroid function test results will have the following characteristics in Graves' disease: TSH, decreased; fT₄, increased; fT₃, increased; T₃RU, increased; TSI, positive; TPO-ab, may be positive; thyroid scan uptake, uniformly increased.

Question 6

Which of the following thyroid hormones normally peak at 24 to 36 hours post-delivery in a newborn and gradually fall over the first 4 weeks of life?&#10;A)total T&#8324;&#10;B)fT4&#10;C)T&#8323;&#10;D)all of the above

Accepted Answer

Within 30 to 60 minutes of delivery, TSH surges and then settles to 6 to 10 U/L by 1 week of age.The TSH surge stimulates thyroidal T₄ secretion, and total T₄, fT₄, and T₃ peak at 24 to 36 hours post-delivery and then gradually fall over the first 4 weeks of life.

Question 7

In patients with developing subclinical hyperthyroidism, TSH levels will likely be ______, and fT&#8324; will likely be ______.&#10;A)decreased, increased&#10;B)increased, decreased&#10;C)decreased, normal&#10;D)increased, normal

Accepted Answer

When screening for disease, laboratory results are often obtained in which the more sensitive test, TSH, is outside of the reference interval, but the free T₄ or free T₃ results are within their reference interval.When patients in these cases are without clinical symptoms of thyroid disease, the situation may be termed subclinical hypothyroidism or hyperthyroidism.Although overt thyroid disease may not be seen until more extremely abnormal TSH levels are achieved, the value of detecting subclinical diseases is becoming important.

Question 8

Which amino acid residue of thyroglobulin is responsible for binding iodine in the formation of thyroid hormones?&#10;A)tyrosine&#10;B)phenylalanine&#10;C)histidine&#10;D)guanidine

Accepted Answer

Intracellular thyroglobulin serves as a preformed matrix containing 123 tyrosine residues to which reactive iodine is attached to form monoiodotyrosine (MIT) and diiodotyrosine (DIT).Most iodination occurs when thyroglobulin is within the exocytic vesicles of the follicular cells.After their formation, enzymatic coupling of MIT and DIT takes place to form intrathyroglobulin T₃ and T₄.

Question 9

During pregnancy, serum TBG concentration ______, total thyroid hormone levels are ______, and free thyroid hormone levels are ______.&#10;A)increases, increased, unaffected&#10;B)is unaffected, increased, increased&#10;C)decreases, decreases, unaffected&#10;D)is unaffected, decreased, decreased

Accepted Answer

During pregnancy, serum TBG concentration increases almost twofold because estrogen increases hepatic TBG production and TBG sialylation.TBG sialylation refers to the addition of a sialic acid residue to TBG, resulting in decreased clearance of TBG.As a result, there is increased total T₄ and total T₃ in the blood stream, because there is more protein to bind the hormones.The free forms of these hormones, however, are not affected by the change in protein concentration and are the analytes of choice to evaluate thyroid hormone levels during pregnancy.

Question 10

Thyroid hormones are metabolized predominantly by deiodination.Which of the following statements are true of deiodinase D1?
1)It is present in high concentration in liver and kidney.
2)It is the main source of T₃ in hyperthyroid patients.
3)It converts T₄ to equimolar amounts of T₃ and rT₃.
4)Its activity is sensitive to changes in serum T₄ and T₃.

A)1, 2, 3
B)1, 2, 4
C)1, 3, 4
D)2, 3, 4

Accepted Answer

There are 3 deiodinases which are known as D1, D2, and D3.D1 is present in high concentration in liver and kidney and converts T₄ to T₃ and rT₃ in equimolar quantities.This enzyme is the main source of T₃ in hyperthyroid patients and is inhibited by the antithyroid drug propylthiouracil.D2 is present in high concentration in muscle, brain, skin, and placenta.Although the activity of D1 is not sensitive to changes in serum T₄ and T₃, the activities of D2 and D3 are sensitive to these levels and change in a reciprocal manner to hormone concentration to maintain homeostasis.

Question 11

When free thyroxine cannot be measured directly, the free thyroxine index (FT&#8324;I) may be calculated by using which measured laboratory data?&#10;A)TSH and T&#8323; resin uptake&#10;B)T&#8324; and T&#8323;resin uptake&#10;C)TSH and T&#8324;&#10;D)T&#8323; and T&#8323;resin uptake

Accepted Answer

The answer of When free thyroxine cannot be measured directly,...

Question 12

Which of the following thyroid hormones is considered to be the most active physiologically?&#10;A)MIT&#10;B)DIT&#10;C)T&#8323;&#10;D)T&#8324;

Accepted Answer

The answer of Which of the following thyroid hormones is...

Question 13

The T&#8323; resin uptake test is used to measure:&#10;A)total T&#8323;&#10;B)free T&#8323;&#10;C)thyroxine binding globulin (TBG)&#10;D)TSH

Accepted Answer

The answer of The T&#8323; resin uptake test is used...

Question 14

There is concern that the upper reference interval value for TSH is set too high to detect subtle hypothyroid disease.It is suggested that the upper reference interval value be reduced to what level to address this concern?

A)5.0 mU/L
B)4.0 mU/L
C)3.0 mU/L
D)2.0 mU/L

Accepted Answer

The answer of There is concern that the upper reference...

Question 15

Which of the following steps in thyroid hormone synthesis, storage, and release are stimulated by TSH?
1)the uptake of amino acids for use in the synthesis of thyroglobulin
2)the uptake of iodine for use in the formation of thyroid hormones
3)the hydrolysis of the thyroglobulin complex to free thyroid hormones
4)thyroid hormone secretion

A)1, 2, 3
B)1, 2, 4
C)1, 3, 4
D)2, 3, 4

Accepted Answer

The answer of Which of the following steps in thyroid...

Question 16

Which of the following characteristics are true of Graves' disease?
1)It is the most common cause of hyperthyroidism.
2)It is more prevalent in men than in women.
3)It is an autoimmune disorder.
4)Patients often have high serum concentration of antibodies against thyroglobulin and thyroid peroxidase.

A)1, 2, 3
B)1, 2, 4
C)1, 3, 4
D)2, 3, 4

Accepted Answer

The answer of Which of the following characteristics are true...

Question 17

The following laboratory data are suggestive of which clinical situation?
TSH - decreased
T₄ - decreased
T₃ - decreased
RT₃ - increased

A)development of a goiter
B)euthyroid sick syndrome
C)Hashimoto's thyroiditis
D)Graves' disease

Accepted Answer

The answer of The following laboratory data are suggestive of...

Question 18

In primary hyperthyroidism, fT&#8324; will be ______, and TSH will be _____.&#10;A)increased, decreased&#10;B)increased, increased&#10;C)decreased, decreased&#10;D)decreased, increased

Accepted Answer

The answer of In primary hyperthyroidism, fT&#8324; will be ______,...

Deck 49: Thyroid