(23) The Thyroid Gland (C)

Question 1

The thyroid gland is responsible for the production of two hormones:

Answer 1

thyroid hormone and calcitonin.

Question 2

The parathyroid glands regulate:

Answer 2

serum calcium levels.

Question 3

Congenital Hypothyroidism can lead to what conditions in newborns?

Answer 3

Mental retardation & cretinism (impaired physical or mental development).

Question 4

Thyroid hormone is made primarily of what trace element?

Answer 4

Iodine.

Question 5

What are the two active forms of thyroid hormone?

Answer 5

Triiodothyronine (T3) & Thyroxine (T4)

Question 6

What thyroid hormone is the most metabolically active?

Answer 6

T3 (3 - 8X more active)

Question 7

What are the three major binding proteins for thyroid hormones?

Answer 7

(1) Thyroxine-binding Globulin
(2) Thyroxine-binding Prealbumin
(3) Albumin

Question 8

The most useful test for assessing thyroid function is:

Answer 8

Thyroid-Stimulating Hormone (TSH).

Question 9

What is the benefit of TSH chemiluminometric assays over other methods?

Answer 9

(1) Increased sensitivity
(2) Fewer false-negatives
(3) Able to distinguish between euthyroidism and hyperthyroidism

Question 10

What are the two common testing methodologies for T4 & T3?

Answer 10

(1) Radioimmunoassay (RIA)
(2) Chemiluminometric assay

Question 11

Thyroglobulin is a protein synthesized and secreted by:

Answer 11

Thyroid follicular cells.

Question 12

What test is an ideal tumor marker thyroid cancer posttreatment surveillance?

Answer 12

Thyroglobulin

Question 13

Thyroglobulin is measured by what testing methodology?

Answer 13

(1) Double-antibody RIA
(2) Enzyme-linked immunoassay (ELISA)
(3) Immunoradiometric assay (IRMA)
(4) Immunochemiluminescent assay (ICMA)

Question 14

What substance can interfere with thyroglobulin testing?

Answer 14

Antithyroglobulin autoantibodies.

Question 15

What is the most common cause of hyperthyroidism?

Answer 15

Graves’ disease (autoimmune disorder).

Question 16

Describe how Graves’ disease causes hyperthyroidism.

Answer 16

Antibodies are directed at TSH receptors, stimulating the receptor and causing an overproduction of thyroid hormone.

Question 17

Describe how Hashimoto’s Thyroiditis causes hypothyroidism.

Answer 17

Antibodies lead to decreased thyroid hormone production by destruction of the thyroid gland (most common cause of hypothyroidism).

Question 18

What is the best test to test for Hashimoto’s Thyroiditis?

Answer 18

TPO antibody.

Question 19

Define radioactive iodine uptake (RAIU).

Answer 19

The percentage of iodine that is taken up by the thyroid gland after oral radioactive iodine is given.

Question 20

How is FT4 and TSH affected by hypothyroidism.

Answer 20

Low FT4; normal or high TSH.

Question 21

What are the physical signs of hypothyroidism?

Answer 21

Bradycardia & diastolic hypertension.

Question 22

What are the symptoms of hypothyroidism?

Answer 22

Cold intolerance, depression, mental retardation.

Question 23

The most common cause for hypothyroidism is:

Answer 23

Lymphocytic thyroiditis, or Hashimoto’s thyroiditis.

Question 24

Hashimoto’s thyroiditis is an ________ disease targeting the ________.

Answer 24

autoimmune; thyroid gland.

Question 25

Hashimoto's thyroiditis is often associated with what physical symptoms?

Answer 25

Enlarged gland, or goiter.

Question 26

What test is often positive when patients present with chronic lymphocytic thyroiditis?

Answer 26

TPO antibody.

Question 27

Transient hypothyroidism is associated with:

Answer 27

inflammation of the thyroid gland.

Question 28

Primary hypothyroidism is from a dysfunction of:

Answer 28

the thyroid gland.

Question 29

Secondary hypothyroidism is from a dysfunction of:

Answer 29

pituitary.

Question 30

Tertiary hypothyroidism is from a dysfunction of:

Answer 30

hypothalamic.

Question 31

How is hypothyroidism treated?

Answer 31

Thyroid replacement therapy (Levothyroxine [T4]).

Question 32

Define Thyrotoxicosis.

Answer 32

When peripheral tissues are presented with an excess of thyroid hormone.

Question 33

What is the most common cause of thyrotoxicosis?

Answer 33

Graves' disease.

Question 34

Graves' disease is a disease in which:

Answer 34

antibodies are produced that activate TSHR.

Question 35

What laboratory testing would indicate Graves' disease (hyperthyroidism)?

Answer 35

High FT4; High FT3; Low/Undetectable TSH.

Question 36

Describe the Wolff-Chaikoff effect.

Answer 36

When iodine is given in large doses, this acutely leads to inhibition of thyroid hormone production.

Question 37

Postpartum thyroiditis is strongly associated with the presence of:

Answer 37

TPO antibodies and chronic lymphocytic thyroiditis.

Question 38

Painful thyroiditis is characterized by what symptoms?

Answer 38

Neck pain, low-grade fever, and swings in thyroid function testing.

Question 39

Describe nonthyroidal illness or euthyroid sick syndrome.

Answer 39

Hospitalized/critically ill patients that have abnormalities on thyroid function testing without thyroid dysfunction.

Question 40

What is the laboratory pattern for nonthyroidal illness or euthyroid sick syndrome.

Answer 40

Normal/low TSH; low T3; low FT4.