Thyroid Medications and Adrenal Disorders

Which hormone is synthesized in the hypothalamus and stimulates the release of TSH from the anterior pituitary?

• Thyroxine

• Thyrotropin-releasing hormone

• Triiodothyronine

• Dopamine

Which of the following inhibits TSH secretion?

• TRH

• Dopamine

• Low plasma T₃ and T₄

• Somatotropin

Which enzyme catalyzes both the iodination of tyrosine and the coupling reactions to form T₃ and T₄?

• Thyroidal peroxidase

• 5′-deiodinase

• Sodium/iodide symporter

• Tyrosine hydroxylase

The sodium/iodide symporter (NIS) is responsible for:

• Transporting iodine into the follicular lumen

• Transporting iodide from plasma into thyroid follicular cells

• Coupling MIT and DIT to form T₄

• Converting T₄ to T₃ in peripheral tissues

Peripheral conversion of T₄ to T₃ occurs mainly via:

• 5′-deiodinase

• Thyroidal peroxidase

• Tyrosinase

• Na⁺/K⁺-ATPase

Thyroid hormone receptors (TRα and TRβ) belong to which receptor family?

• G protein–coupled receptors

• Nuclear receptor family

• Ligand-gated ion channels

• Tyrosine kinase receptors

Which of the following is not a physiologic effect of thyroid hormone?

• Increased basal metabolic rate

• Decreased protein degradation

• Enhanced cardiac output

• Increased lipolysis

Hashimoto’s thyroiditis is primarily characterized by:

• Excessive secretion of T₃ and T₄

• Autoimmune destruction of the thyroid gland

• Iodine-induced thyrotoxicosis

• Pituitary adenoma causing TSH overproduction

Graves’ disease results from:

• TSH receptor-blocking antibodies

• Iodine deficiency

• TSH receptor–stimulating antibodies

• Pituitary tumor producing ACTH

Which thyroid preparation is preferred for replacement therapy in hypothyroidism?

• Liothyronine

• Liotrix

• Levothyroxine

• Desiccated thyroid