Which of the following hormone is not involved in tyrosine metabolism

Options

A. Calcitionin
B. Melanin
C. Thyroxine
D. Epinephrine.

Answer

To determine which hormone is not involved in tyrosine metabolism, we will analyze each of the given options: calcitonin, melanin, thyroxine, and epinephrine.

### Step-by-step Solution:

1. **Understand Tyrosine Metabolism**:
- Tyrosine is a non-essential amino acid that is derived from phenylalanine. It plays a crucial role in the synthesis of several important substances in the body.

2. **Identify Hormones Related to Tyrosine**:
- **Thyroxine (T4)**: This hormone is produced by the thyroid gland and is synthesized from tyrosine. Therefore, it is involved in tyrosine metabolism.
- **Epinephrine (Adrenaline)**: This hormone is a catecholamine derived from tyrosine. It is involved in the body’s fight-or-flight response and is also part of tyrosine metabolism.
- **Melanin**: This is a pigment produced from tyrosine. It is involved in the coloration of skin, hair, and eyes, indicating its connection to tyrosine metabolism.

3. **Analyze Calcitonin**:
- **Calcitonin**: This hormone is produced by the parafollicular cells (C cells) of the thyroid gland. Its primary function is to regulate calcium and phosphate levels in the body. Importantly, calcitonin is not synthesized from tyrosine and does not require tyrosine as a precursor.

4. **Conclusion**:
- Based on the analysis, calcitonin is the hormone that is not involved in tyrosine metabolism. The correct answer is **calcitonin**.

### Final Answer:
The hormone that is not involved in tyrosine metabolism is **calcitonin**.

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