Question

Deficiency of iodine results in

• A. Goitre
• B. Exophthalmia
• C. Grave's disease
• D. Cretinism

Answer 1

Answer: (A)

Goitre

Thyroxine and triiodothyronine are thyroid hormones which target all tissues and stimulate metabolic rate, growth and development. Thyroxine has four iodine atoms while triiodothyronine has three iodine atoms. The dietary iodine serves as source and thus iodine deficient diet renders the gland unable to synthesize the hormones. Under these conditions, constant stimulation of thyroid gland by anterior pituitary to secrete hormones leads to enlargement of thyroid gland; the simple goiter. This makes option A correct. Oversecretion of thyroid hormones (hyperthyroidism) causes Graves’s disease which is characterized by formation of exopthalamic goiter. This makes options B and C incorrect. Option D is incorrect as cretinism is caused by failure of proper development of thyroid gland, not by iodine deficiency. Correct answer is A.