[Campbell Biology P.1067] Which of the following is the most likely explanation for hypothyro... | Practice Question

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 TSH
  • C: Hypersecretion of MSH
  • D: A decrease in the thyroid secretion of calcitonin

Explanation

Hypothyroidism results from insufficient thyroid hormone production. If iodine levels are normal, the issue is not a lack of raw materials for thyroid hormones. TSH thyroid-stimulating hormone from the pituitary gland stimulates the thyroid. If TSH secretion is low hyposecretion , the thyroid would not be adequately stimulated, leading to decreased thyroid hormone production and thus hypothyroidism. This is a secondary form of hypothyroidism.