Endemic goitre is a state of

• increased thyroid function

• normal thyroid function

• decreased thyroid function

• moderate thyroid function

A.

increased thyroid function

The most common type of goitre is endemic goitre, caused by iodine deficiency. Iodine is an essential nutrient that is required for the production of thyroid hormone. When iodine intake is low, thyroid hormone production is low, and in response the pituitary gland secretes greater quantities of the hormone thyrotropin or thyroid stimulating hormone (TSH). This excess thyrotropin stimulates not only thyroid hormone production but also thyroid growth.