Question

Goitre can occur as a consequence of all except

• A. Graves' disease
• B. Iodine defiency
• C. Pituitary adenoma
• D. Excessive intake of exogenous thyroxine

Answer 1

Answer: (D)

Excessive intake of exogenous thyroxine

Goitre is the enlargement of thyroid gland which occurs due to deficiency of iodine in the body. Iodine is needed for the synthesis of thyroid hormone. When the iodine levels are low, thyroid gland becomes hyper active and enlarged to compensate the deficiency of thyroid hormone in the body. The enlarged thyroid gland is visible as a swelling in the throat known as goitre.

Grave's disease or exophthalmic goitre occurs due to over secretion of thyroid hormone as the thyroid gland becomes hyperactive. In exophthalmic goitre, protrusion of eyeballs occur due to deposition of excess fat behind the eyes.

Thyroid gland may also become hyperactive due to hypersecretion of TSH (Thyroid stimulating hormone) from anterior pituitary and this can occur due to pituitary adenoma (benign tumours of pituitary gland).

Excessive intake of exogenous thyroxine can't cause goitre.

So, the correct answer is 'Excessive intake of exogenous thyroxine'.