Deck 42: Thyroid Disorders

Question 1

What is required for normal thyroxine synthesis?

A) Iodine
B) Iodine and thyroglobulin
C) Iodine and thyroid-binding globulin
D) TSH,iodine,and thyroglobulin

Answer 1

TSH,iodine,and thyroglobulin

Question 2

An amorphous material enclosed within each follicle of the thyroid gland and that is composed mainly of thyroglobulin is:

A) thyroxine.
B) iodine.
C) colloid.
D) goiter.

Answer 2

colloid.

Question 3

Increased TSH,decreased T₃,and decreased T₄ with the presence of goiter indicate:

A) primary hypothyroidism.
B) secondary hypothyroidism.
C) tertiary hypothyroidism.
D) pseudohypothyroidism.

Answer 3

primary hypothyroidism.

Question 4

Thyroid-stimulating hormone (TSH)receptor antibodies can be detected in serum of patients having which of the following?

A) Multinodular goiter
B) Thyroid tumors
C) Thyrotoxicosis
D) Graves disease

Question 5

The secretory unit of the thyroid gland is the:

A) colloid.
B) thyroid follicle.
C) parafollicular cell.
D) thymus.

Question 6

Myxedema is a skin and tissue mucopolysaccharide disorder caused by severe and prolonged:

A) Graves disease.
B) hypothyroidism.
C) hyperthyroidism.
D) thyrotoxicosis.

Question 7

An individual's thyroid-binding globulin (TBG)concentration is 2.8 mg/dL,T₃ value is 10.5 µg/dL,and T₄ value is 12.5 µg/dL.What is the estimate of free T₄ value?

A) 37.5
B) 4.3
C) 1.35
D) The approximate free T₄ value cannot be determined from the given values.

Question 8

Regarding thyroid hormones,the primary secretory product of the normal thyroid gland is in the form of:

A) free thyroxine (T₄).
B) free triiodothyronine (T₃).
C) iodine.
D) thyroglobulin (Tg).

Question 9

Which of the following hormones require transport proteins to move them through the circulation and are more than 99% bound to these proteins?

A) TSH
B) Thyrotropin-releasing hormone
C) Calcitonin
D) T₃ and T₄

Question 10

A 30-year-old man visits his physician for an annual health check.He complains that he has been feeling fatigued of late and has lost weight.Blood is collected and the following laboratory results are noted: total T₃,elevated; total T₄,elevated; free T₄,elevated; TSH,slightly elevated.Magnetic resonance imaging indicates a mass in the area of his pituitary gland.What disorder do the results suggest?

A) Central hyperthyroidism
B) Graves disease
C) Secondary hypothyroidism
D) TSH-secreting pituitary tumor

Question 11

Severe hypothyroidism that develops during the newborn period is referred to as:

A) thyrotoxicosis.
B) myxedema.
C) cretinism.
D) euthyroid sick syndrome.

Question 12

Thyroid hormones are derived from the amino acid:

A) phenylalanine.
B) threonine.
C) theophylline.
D) tyrosine.

Question 13

A 45-year-old woman visits her physician with complaints of fatigue,heat intolerance,goiter,and unusual hair loss.Blood is collected and serum T₄ value is below the healthy reference interval.What laboratory assay would confirm that this might be a pituitary disorder?

A) Free T₃
B) Thyroid-binding globulin (TBG)
C) Thyrotropin-releasing hormone (TRH)
D) Thyroid-stimulating hormone (TSH)

Question 14

A woman with thyroid cancer has her thyroglobulin (Tg)level checked to assess return of thyroid function following surgery.The Tg value was markedly decreased.Her physician calls the laboratory asking for an explanation of the result.You respond that:

A) this is a typical value for someone with thyroid cancer and that Tg can be used as a tumor marker,so decreased values are better than increased values.
B) Tg is probably being interfered with by the immunoglobulins that are involved in the healing postsurgery process.
C) your laboratory uses a Tg assay that likely has been interfered with by Tg autoantibodies,which limits the accurate measurement of Tg.
D) thyroid cancer obliterates all colloid in the thyroid gland and therefore Tg will not be present in a blood sample.

Question 15

Another term used to describe hyperthyroidism is:

A) goiter.
B) euthyroid sick syndrome.
C) thyrotoxicosis.
D) cretinism.

Question 16

Which one of the following is not a function of the thyroid hormones?

A) Control of metabolic rate
B) Removal of defective RBCs
C) Increasing cholesterol synthesis and breakdown
D) Stimulation of neural development

Question 17

Serum thyroid-stimulating hormone (TSH)level is decreased in individuals with:

A) hyperthyroidism.
B) primary hypothyroidism.
C) secondary hyperthyroidism.
D) primary hyperparathyroidism.

Question 18

Which one of the following statements is correct regarding reverse T₃ (rT₃)?

A) rT₃ is physiologically active,but less so than T₃.
B) rT₃ is formed in the blood by central deiodination of T₄.
C) rT₃ is decreased in patients with the "euthyroid sick syndrome."
D) Renal failure is associated with elevated rT₃ concentrations.

Question 19

What causes the total thyroxine (T₄)levels to be increased in pregnant women?

A) Inappropriate iodine metabolism
B) hCG-induced thyrotoxicosis
C) Altered glucose metabolism
D) Change in thyroglobulin synthesis

Question 20

The limited clinical information that is available from the results of a total T₄ measurement is due to:

A) interferences with circulating autoantibodies directed against the colloid.
B) the formation of fibrin clots during the preparation of the blood sample.
C) the fact that total T₄ measurements reflect inactive,protein-bound hormone.
D) the fact that circadian rhythms are not determined.