Hypocalcaemia means

Options

A. High level of potassium in blood
B. High level of sodium in blood
C. Low level of potassium in blood
D. Low level of sodium in blood

Explanation

### Step-by-Step Text Solution:

1. **Understanding the Term "Hypocalcemia":**
- The term "hypocalcemia" is derived from the prefix "hypo-" meaning low, and "calcemia" which refers to calcium levels in the blood. Therefore, hypocalcemia specifically refers to low levels of calcium in the blood.

2. **Identifying the Normal Calcium Levels:**
- Normal blood calcium levels typically range from about 8.5 to 10.2 mg/dL. When levels fall below this range, it is classified as hypocalcemia.

3. **Hormonal Regulation of Calcium Levels:**
- Two primary hormones are involved in regulating calcium levels in the blood:
- **Thyrocalcitonin (Calcitonin):** This hormone is produced by the thyroid gland and functions to lower blood calcium levels by promoting the deposition of calcium in bones and inhibiting calcium release from bones.
- **Parathormone (Parathyroid Hormone):** This hormone is produced by the parathyroid glands and works to increase blood calcium levels by stimulating the release of calcium from bones, increasing calcium absorption in the intestines, and promoting calcium reabsorption in the kidneys.

4. **Consequences of Hypocalcemia:**
- When there is a low level of calcium in the blood, it can lead to various health issues, one of which is tetany. Tetanus is characterized by muscle spasms and cramps due to the excitability of the nervous system when calcium levels are inadequate.

5. **Conclusion:**
- Therefore, hypocalcemia is defined as a condition where there is a low level of calcium in the blood, regulated by the hormones thyrocalcitonin and parathormone.