Which of the following hormones is synthesised by using tyrosine as a precursor?

Options

A. Thyrocalcitonin
B. Thyroxine
C. GH
D. ACTH

Answer

To determine which hormone is synthesized using tyrosine as a precursor, we can analyze the options provided:

1. **Thyrocalcitonin**: This hormone is secreted by the thyroid gland and is involved in regulating calcium levels in the blood. However, it is not synthesized from tyrosine.

2. **Thyroxine (T4)**: This hormone is indeed synthesized by the thyroid gland. It is formed from the amino acid tyrosine and iodine. Thyroxine plays a crucial role in regulating metabolism in the body.

3. **Growth Hormone (GH)**: This hormone is produced by the pituitary gland and is responsible for growth and development. Its synthesis does not involve tyrosine.

4. **Adrenocorticotropic Hormone (ACTH)**: This hormone is produced by the anterior pituitary gland and stimulates the adrenal glands. Its precursor is not tyrosine.

From this analysis, we can conclude that the hormone synthesized using tyrosine as a precursor is **Thyroxine**.

### Step-by-Step Solution:
1. **Identify the hormones listed**: The options provided are thyrocalcitonin, thyroxine, growth hormone, and adrenocorticotropic hormone.

2. **Analyze each hormone**:
- **Thyrocalcitonin**: Secreted by the thyroid, but not derived from tyrosine.
- **Thyroxine (T4)**: Synthesized from tyrosine and iodine; correct answer.
- **Growth Hormone (GH)**: Secreted by the pituitary gland, not derived from tyrosine.
- **Adrenocorticotropic Hormone (ACTH)**: Produced by the anterior pituitary, not derived from tyrosine.

3. **Conclude the correct answer**: The hormone synthesized using tyrosine as a precursor is **Thyroxine**.