Which of the following statements is true about the synthesis of thyroid hormone and its physiology?
A. The iodine utilized in hormone synthesis is derived principally from dietary sources.
B. The role of thyroid-stimulating hormone (TSH) in thyroid physiology is limited to regulation of the release of thyroid hormone in plasma.
C. Enough thyroxine (T 4) is stored in the normal thyroid to provide a euthyroid state for 3 weeks despite absence of iodine intake.
D. The regulation of thyroid function involves pituitary, but not hypothalamic, input.
Answer:A
Which of the following statements is true about the synthesis of thyroid hormone and its physiology?
A. The iodine utilized in hormone synthesis is derived principally from dietary sources. B. The role of thyroid-stimulating hormone (TSH) in thyroid physiology is limited to regulation of the release of thyroid hormone in plasma. C. Enough thyroxine (T 4) is stored in the normal thyroid to provide a euthyroid state for 3 weeks despite absence of iodine intake. D. The regulation of thyroid function involves pituitary, but not hypothalamic, input.