Raju had a thyroid test. His doctor gave him an injection of TSH and 15 minutes later measured the level of thyroid hormone in his blood. What is TSH? Why do you think Raju's doctor gave him an injection of TSH? How would this affect the level of thyroid hormone in his blood if his thyroid is normal?

Explanation

### Step-by-Step Solution:

1. **Understanding TSH**:
- TSH stands for Thyroid Stimulating Hormone. It is a hormone produced by the anterior pituitary gland in the brain. TSH plays a crucial role in regulating the production of thyroid hormones (T3 and T4) from the thyroid gland.

2. **Purpose of TSH Injection**:
- Raju's doctor administered TSH to stimulate the thyroid gland. This is typically done to assess how well the thyroid gland responds to stimulation. By injecting TSH, the doctor can evaluate the function of the thyroid gland and determine if it is producing adequate levels of thyroid hormones.

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