The Thyroid Gland

All of the following statements about iodine are true EXCEPT a. Radioactive iodine treatment of Graves disease is effective in less than 40% of patients treated with this agent. b. Iodine deficiency is one of the most common causes of hypothyroidism in the world. c. T4 has four iodine molecules. d. RAIU is often useful in determining the cause of thyrotoxicosis.

• The fetus a. Is dependent on thyroid hormone for normal neurologic development b. Does not develop a thyroid gland until the third trimester c. Is not susceptible to damage from radioactive iodine therapy given to the mother d. Will be born with hypothyroidism in approximately 1 of 400 births in developed countries

The thyroid gland a. Depends on TPO to permit iodination of the tyrosyl residues to make MIT and DIT b. Is an ineffective iodine trap c. Depends on TPO to permit the joining of two DIT residues to form T3 d. Usually functions independent of TSH levels

The thyroid gland produces all of the following EXCEPT a. TSH b. Thyroglobulin c. T3 d. T4

Hypothyroidism is generally associated with all of the following EXCEPT a. TSH receptor antibodies b. Depression c. An elevation of TSH levels d. TPO antibodies

• A 34-year-old woman presents with goiter, tachycardia, and weight loss of 2 months duration. TSH is undetectable and free T4 is high. All of the following tests are useful in diagnosing the cause of the hyperthyroidism EXCEPT a. FNA biopsy of the thyroid gland b. TSH receptor antibodies c. RAIU d. TSH

A 65-year-old woman presents with fatigue, hypothermia, pericardial effusions, and hair loss. Her thyroid function tests show a significantly elevated TSH and a low free T4 . All of the following laboratory test abnormalities may be associated with her underlying condition EXCEPT a. Elevated WBC b. An elevated cholesterol level c. Anemia d. Elevated CPK levels

A 26-year-old man presents with a 3-cm, right lobe, thyroid nodule and a normal TSH. What is the next test that should be performed? a. FNA of the nodule b. Free T4 level c. Thyroid ultrasound d. Thyroid scan

The following are treatment options for hyperthyroidism associated with Graves’ disease EXCEPT a. Thyroid hormone b. PTU c. Beta-blockers d. Radioactive iodine

All of the following abnormalities might be expected in a severely ill patient EXCEPT a. Low rT3 b. Low T4 c. Low T3 d. Low TSH

Of the following thyroid hormones, which is considered the most biologically active? a. T3 bound to TBG b. T4 bound to TBG c. Free T4 d. Free T3 e. rT3

The primary serum test to screen for thyroid disease is a. Free T4 b. rT3 c. Total T4 d. Autoimmune antibodies to thyroid tissue e. TSH

Of the following, which will MOST likely interfere with quantitation of thyroglobulin? a. Antithyroglobulin autoantibodies b. Thyroid-stimulating antibodies c. TSH receptor antibodies d. Thyroid peroxidase antibodies