The under secretion of thyroxine in children results in?

Step 1: Analyze the question The question asks what happens when a child's thyroid gland produces too little thyroxine (hypothyroidism, or hyposecretion).

Step 2: Explain the concept Thyroxine is produced by the thyroid gland in the neck. It controls metabolic rate and is essential for normal physical and mental growth.

• Under secretion (hyposecretion) in children: cretinism
• Under secretion in adults: myxoedema
• Over secretion (hypersecretion): exophthalmic goitre (Graves' disease), with a high metabolic rate, weight loss, and bulging eyes
• Simple goitre: swelling of the thyroid gland, usually caused by a lack of iodine in the diet

Step 3: Evaluate each option

• A. Goitre: This is an enlarged thyroid gland, usually from iodine deficiency. It is not the specific condition of thyroxine deficiency in children. It is the tempting wrong answer, because iodine deficiency can lead to low thyroxine, but the question asks for the condition in children.
• B. Gigantism: This results from over secretion of growth hormone in childhood (from the pituitary gland), so it is not a thyroid problem.
• C. Kwashiorkor: This is a protein-deficiency disease and has nothing to do with hormones.
• D. Cretinism: This is correct. Children with too little thyroxine have stunted growth, a low metabolic rate, delayed mental development, a thick protruding tongue, and a pot belly.

Step 4: Answer The correct option is D. cretinism.

Exam tip: Remember the pairing "Children → Cretinism" (both start with C), and "Adults → Myxoedema". For gigantism, think "Growth hormone, Giant".