The secretion of which of these hormones would be increased in a person with endemic goitre ?

Options

A. TSH
B. Thyroxine
C. Triiodothyronine
D. All of these

Answer

To determine which hormone's secretion would be increased in a person with endemic goitre, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Endemic Goitre**: Endemic goitre is primarily caused by iodine deficiency. In regions where there is insufficient iodine in the diet, the thyroid gland cannot produce enough thyroid hormones.

2. **Identify the Role of Thyroid Hormones**: The main hormones produced by the thyroid gland are thyroxine (T4) and triiodothyronine (T3). These hormones are crucial for regulating metabolism, growth, and development.

3. **Recognize the Feedback Mechanism**: When iodine levels are low, the production of thyroid hormones (T3 and T4) decreases. This reduction triggers the pituitary gland to secrete more thyroid-stimulating hormone (TSH) to stimulate the thyroid gland to produce more thyroid hormones.

4. **Evaluate the Options**:
- **TSH (Thyroid Stimulating Hormone)**: This hormone is secreted by the pituitary gland and stimulates the thyroid gland to produce T3 and T4.
- **Thyroxine (T4)**: This is one of the main hormones produced by the thyroid gland, but its production is low due to iodine deficiency.
- **Triiodothyronine (T3)**: Similar to T4, this hormone is also produced by the thyroid gland but is dependent on iodine availability.
- **All of these**: This option suggests that all mentioned hormones would be increased.

5. **Conclusion**: In a person with endemic goitre, the secretion of TSH would be increased as the body attempts to stimulate the thyroid gland to produce more thyroid hormones (T3 and T4), which are low due to iodine deficiency. Therefore, the correct answer is TSH.

### Final Answer:
The secretion of **TSH (Thyroid Stimulating Hormone)** would be increased in a person with endemic goitre.

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