Question

How are TSH and thyroxine related?

• A. They are both produced by the same gland.
• B. When thyroxine is in excess, TSH levels are low.
• C. They both help to maintain the sugar levels in the blood.
• D. They are not related at all.

Answer 1

The correct option is B

When thyroxine is in excess, TSH levels are low.

If the level of thyroxine in the blood is low, then the pituitary releases more TSH to try to stimulate the thyroid gland to make more thyroxine. Therefore, a raised level of TSH means the thyroid gland is underactive and is not making enough thyroxine.