Which of the following hormones regulate calcium balance in body ?

Options

A. TCT
B. PTH
C. ADH
D. Both A & B

Answer

To determine which hormones regulate calcium balance in the body, we need to analyze the roles of specific hormones involved in calcium homeostasis. The two primary hormones that play significant roles in regulating calcium levels are Thyrocalcitonin (TCT) and Parathyroid Hormone (PTH).

### Step-by-Step Solution:

1. **Identify Thyrocalcitonin (TCT)**:
- TCT, also known as calcitonin, is secreted by the parafollicular cells of the thyroid gland.
- It is released when blood calcium levels are high.

**Hint**: Remember that TCT works to lower blood calcium levels.

2. **Function of Thyrocalcitonin**:
- TCT decreases blood calcium levels by:
- Promoting calcium deposition in bones (bone deposition).
- Reducing calcium reabsorption from the gut.
- Decreasing calcium reabsorption in the kidneys.

**Hint**: Think of TCT as a hormone that "tones down" calcium levels in the blood.

3. **Identify Parathyroid Hormone (PTH)**:
- PTH is secreted by the parathyroid glands, which are located near the thyroid gland.
- It is released when blood calcium levels are low.

**Hint**: PTH is the hormone that "raises" calcium levels in the blood.

4. **Function of Parathyroid Hormone**:
- PTH increases blood calcium levels by:
- Stimulating bone resorption (releasing calcium from bones).
- Increasing calcium absorption from the gut.
- Decreasing calcium excretion in the kidneys.

**Hint**: PTH acts like a "pulling force" to release calcium into the bloodstream.

5. **Conclusion**:
- Both TCT and PTH are crucial in maintaining calcium homeostasis in the body.
- TCT lowers calcium levels, while PTH raises them, working antagonistically to regulate calcium balance.

**Final Answer**: The hormones that regulate calcium balance in the body are both Thyrocalcitonin (TCT) and Parathyroid Hormone (PTH).