The need of calcium in human body can be fulfilled by either absorption of calcium from the digested food or by reabsorption of calcium from renal tubules , which is accomplished by :

Options

A. PTH
B. Thymosin
C. Mineral corticoids
D. Thyrocalcitonin

Answer

To solve the question regarding the fulfillment of calcium needs in the human body through reabsorption from renal tubules, we will analyze the options provided and identify the correct hormone responsible for this process.

### Step-by-Step Solution:

1. **Understanding the Question**: The question states that calcium needs in the human body can be met by either absorbing calcium from digested food or by reabsorbing calcium from renal tubules. We need to identify which hormone is responsible for the reabsorption of calcium from the renal tubules.

2. **Reviewing the Options**:
- **Option A: PTH (Parathyroid Hormone)**: This hormone is secreted by the parathyroid glands and is known to increase blood calcium levels. It does this by promoting the absorption of calcium from the intestines and the reabsorption of calcium in the kidneys.
- **Option B: Thymosin**: This hormone is produced by the thymus gland and is primarily involved in the immune response. It does not play a role in calcium metabolism.
- **Option C: Mineralocorticoids**: The main mineralocorticoid is aldosterone, which regulates sodium levels and has little to do with calcium reabsorption.
- **Option D: Thyrocalcitonin (Calcitonin)**: This hormone is secreted by the thyroid gland and works to lower blood calcium levels, opposing the action of PTH.

3. **Analyzing PTH**: Since PTH increases blood calcium levels by enhancing calcium absorption in the intestines and promoting reabsorption in the renal tubules, it is the hormone that fulfills the need for calcium in the body.

4. **Conclusion**: The correct answer is **Option A: PTH (Parathyroid Hormone)**, as it is responsible for the reabsorption of calcium from the renal tubules and increasing calcium levels in the blood.