The main cause of anaemia is

Options

A. deficiency of Fe
B. deficiency of Na
C. deficiency of Ca
D. deficiency of Mg

Answer

**Step-by-Step Solution:**

1. **Understanding Anemia**: Anemia is a condition characterized by a decrease in the number of red blood cells (RBCs) or hemoglobin in the blood, leading to reduced oxygen transport in the body.

2. **Identifying Causes of Anemia**: The main causes of anemia can include nutritional deficiencies, chronic diseases, genetic disorders, and bone marrow problems. Among these, nutritional deficiencies are the most common.

3. **Analyzing the Options**:
- **Option 1: Deficiency of Iron**: This is a well-known cause of anemia, specifically iron-deficiency anemia. Iron is essential for the production of hemoglobin, and its deficiency leads to reduced hemoglobin levels and RBC count.
- **Option 2: Deficiency of Sodium**: Sodium deficiency, known as hyponatremia, does not directly cause anemia. It affects fluid balance and nerve function but not RBC production.
- **Option 3: Deficiency of Calcium**: Calcium deficiency, referred to as hypocalcemia, is important for bone health and muscle function but is not a direct cause of anemia.
- **Option 4: Deficiency of Magnesium**: Magnesium deficiency can lead to various health issues, but it is not a primary cause of anemia.

4. **Conclusion**: Based on the analysis, the main cause of anemia among the given options is the deficiency of iron.

**Final Answer**: The main cause of anemia is the deficiency of iron.

---