Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal?
A) greater production of T3 than of T4
B) hyposecretion of thyroid-stimulating hormone (TSH)
C) hypersecretion of thyrotropin-releasing hormone (TRH)
D) a decrease in the thyroid secretion of calcitonin

Question

Quizplus · Accepted Answer

Hypothyroidism is often caused by inadequate production of thyroid hormones by the thyroid gland. When the thyroid gland is not producing enough thyroid hormones, the pituitary gland secretes more thyroid-stimulating hormone (TSH) to try to stimulate the thyroid gland to increase hormone production. Therefore, hypothyroidism is usually associated with elevated TSH levels. However, if the iodine level is normal, it suggests that the thyroid gland itself is not the problem and the issue is with the pituitary gland or hypothalamus, leading to hyposecretion of TSH.

Which of the Following Is the Most Likely Explanation for Hypothyroidism