Under secretion of thyroxine before maturity cause

Analyze the question: The question asks what condition results from under secretion (hyposecretion) of thyroxine before maturity, meaning in infancy or childhood.

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

| Condition | Cause | |---|---| | Cretinism | Hyposecretion of thyroxine in infancy/childhood | | Myxoedema | Hyposecretion of thyroxine in adults | | Simple goiter | Iodine deficiency, which enlarges the thyroid gland | | Exophthalmic goiter (Graves' disease) | Hypersecretion of thyroxine | | Gigantism | Hypersecretion of growth hormone before maturity (pituitary) | | Obesity | Usually overeating or other causes, not a classic thyroxine-deficiency condition |

Solution:

1. The hormone involved is thyroxine, so we can rule out gigantism, which is a growth hormone disorder (B).
2. "Under secretion" means too little, so we rule out the conditions linked to excess.
3. The key phrase is "before maturity", which points to children. In adults, the same deficiency gives myxoedema (D), so D is wrong for this question.
4. Goiter (C) is mainly an enlargement of the gland due to iodine deficiency, not the specific answer for childhood thyroxine deficiency.
5. Obesity (E) is not the standard answer here.

In children, thyroxine deficiency causes stunted growth, delayed mental development, a thick protruding tongue, and a pot belly. This is cretinism.

**Correct answer: A. cretinism.

Exam tip: Remember "Cretinism = Child". Cretinism is for children, and myxoedema is for mature adults (both from too little thyroxine). Check for words like "before maturity" or "in adults" to decide between them.