Chapter 122: Disorders of the Thyroid Gland

Question 1

Hypothyroidism with myxedematous infiltration of the vocal cords has a

Answer 1

Husky, raspy tone of voice

Question 2

A patient whose recurrent laryngeal nerve is compromised by
pressure or tumor infiltration has the voice of a paralyzed vocal
cord

Answer 2

Breathy, barely audible, and inefficient

Question 3

Signifies obstruction of the aerodigestive passage, usually at the level of the tongue base

Answer 3

Guttural quality of voice

Question 4

May signify obstruction of the superior vena cava from benign
or malignant substernal thyroid disease

Answer 4

1. Facial swelling or plethora

2. Distension of the jugular veins

Question 5

Indicates cervicothoracic inlet obstruction

Answer 5

Pemberton sign

1. facial erythema, swelling
2. distension of the jugular veins

Question 6

Superior pole and the lateral lobes drain superiorly and laterally toward the

Answer 6

Jugular lymph nodes

Question 7

Isthmus and lower poles of the thyroid drain inferiorly along the

Answer 7

Tracheoesophageal groove and into the mediastinum

Question 8

Thyroid gland produces two major hormones

Answer 8

1. 3,5,3′-triiodothyronine (T3)

2. 3,5,3′,5′-tetraiodothyronine, or thyroxine (T4)

Question 9

Hormone production depends on

Answer 9

1. External iodine supply and on
2. Intrathyroidal mechanisms for concentrating ingested iodide and then incorporating it into the tissue-specific protein, thyroglobulin

Question 10

Used for storage of the hormones and their precursors

Answer 10

Follicular lumen

Question 11

Required daily dietary intake of iodine in humans to ensure adequate production of thyroid hormone

Answer 11

At least 100 µg of iodine per day

Question 12

Leading cause of thyroid-related disorders

Answer 12

Iodine deficiency

Question 13

Protein located in the basal membrane of the thyroid cell

known as

Answer 13

Sodium/iodide symporter (NIS)

Question 14

An apical membrane protein that aids in releasing iodide into the follicular lumen

Answer 14

Pendrin

Question 15

Associated with mild hypothyroidism, goiter, and hearing loss

Answer 15

Pendred syndrome

Question 16

a tissue specific protein that serves as a matrix for the synthesis of hormone and as a vehicle for its storage

Answer 16

Thyroglobulin

Question 17

Human thyroglobulin gene has been cloned and is located on the long arm of

Answer 17

Chromosome 8q24

Question 18

Composition of thyroglobulin

Answer 18

1. 10% of its weight is carbohydrate

2. 0.1% to 1% is iodine

Question 19

Process in hormone synthesis

Answer 19

1. oxidation of iodide
2. subsequent transfer to thyrosyl residues on thyroglobulin, which produces monoiodotyrosine (MIT) and diiodotyrosine (DIT)
3. coupling of two iodotyrosine molecules, either one each of MIT and DIT to form T3 or two of DIT to form T4

Question 20

An enzyme present in the apical cell membrane, is responsible for iodination

Answer 20

Thyroperoxidase (TPO)

Question 21

Required in the iodinating and coupling reactions, is generated at the apical membrane by a reduced nicotinamide adenine dinucleotide phosphate oxidase

Answer 21

Hydrogen peroxide (H2O2)