A subject consuming a diet deficient in iodine is likely to have
A)A low plasma concentration of thyroxine due to reduced secretion of TSH by the pituitary gland
B)A low plasma concentration of thyroxine and an enlarged thyroid gland
C)A high plasma concentration of TSH
D)A low plasma concentration of thyroxine due to reduced secretion of TSH by the pituitary gland and a low plasma concentration of thyroxine and an enlarged thyroid gland
E)A low plasma concentration of thyroxine and an enlarged thyroid gland and a high plasma concentration of TSH

Question

Quizplus · Accepted Answer

A deficiency in iodine would lead to a decreased production of thyroid hormones. With low levels of thyroid hormones, the pituitary gland would secrete more TSH in an attempt to stimulate the thyroid gland to produce more hormones. This would lead to a high plasma concentration of TSH. However, since there is a deficiency in iodine, the thyroid gland would not be able to produce enough thyroid hormones even with the increased levels of TSH, leading to a low plasma concentration of thyroxine. This condition is known as hypothyroidism and can cause enlargement of the thyroid gland (known as a goiter). Therefore, choice E is the best choice as it reflects all three possible outcomes of a deficiency in iodine.

A Subject Consuming a Diet Deficient in Iodine Is Likely