What is true about calcitonin

Options

A. It is released from thyroid gland
B. It contains iodine
C. It is released from parathyroid
D. It is an amino acid

Answer

### Step-by-Step Solution:

1. **Identify the Source of Calcitonin**:
- Calcitonin is a hormone secreted by the para-follicular cells (also known as C cells) of the thyroid gland.

2. **Understand the Function of Calcitonin**:
- The primary function of calcitonin is to lower the calcium levels in the blood. It achieves this by inhibiting osteoclast activity (cells that break down bone) and promoting the deposition of calcium in the bones.

3. **Evaluate the Options**:
- The question likely provides several statements about calcitonin. We need to determine which of these statements is true.
- Option 1 states that calcitonin is released from the thyroid gland. This is true.
- Option 2 mentions that calcitonin contains iodine. This is false; calcitonin does not contain iodine.
- Option 3 states that calcitonin is released from the parathyroid gland. This is incorrect, as it is released from the thyroid gland.
- Option 4 suggests that calcitonin is an amino acid. This is also false; calcitonin is a peptide hormone.

4. **Conclusion**:
- Based on the evaluation of the options, the only true statement about calcitonin is that it is released from the thyroid gland.

### Final Answer:
The true statement about calcitonin is that it is released from the thyroid gland.