To answer the question regarding what might be expected in a patient with rickets due to Vitamin D deficiency, let's analyze the options step by step.
### Step-by-Step Solution:
1. **Understanding Rickets and Vitamin D Deficiency**:
- Rickets is a condition that affects bone development in children, often due to a deficiency of Vitamin D, calcium, or phosphate. Vitamin D is crucial for calcium absorption in the body.
2. **Evaluating Option 1**:
- **Elevated plasma parathyroid hormone concentration and suppressed osteoclastic activity**:
- Vitamin D deficiency leads to low calcium levels in the blood. In response, the parathyroid hormone (PTH) is released to increase calcium levels, which would elevate its concentration. However, the statement about suppressed osteoclastic activity is incorrect because osteoclasts are responsible for bone resorption, which would be increased in response to low calcium levels. Thus, this option is not correct.
3. **Evaluating Option 2**:
- **Low plasma concentration of 1,25-Dihydroxycholecalciferol**:
- 1,25-Dihydroxycholecalciferol is the active form of Vitamin D. In cases of Vitamin D deficiency, the levels of this active form are indeed low. Therefore, this option is correct.
4. **Evaluating Option 3**:
- **Normal plasma phosphate concentration**:
- In Vitamin D deficiency, calcium absorption is impaired, which also affects phosphate absorption. Typically, phosphate levels would not remain normal; they may actually increase due to decreased absorption in the bones. Hence, this option is incorrect.
5. **Evaluating Option 4**:
- **All of the above**:
- Since we have established that options 1 and 3 are incorrect, this option cannot be correct either.
### Conclusion:
The most accurate answer to the question is **Option 2: Low plasma concentration of 1,25-Dihydroxycholecalciferol**.
