When a partient is treated with an aldosterone antagonist, there is likely to be a fall in

Options

A. urine volume
B. plasma potassium concentration
C. blood viscosity
D. blood volume

Answer

### Step-by-Step Solution:

1. **Understanding Aldosterone and Its Function**:
- Aldosterone is a hormone produced by the adrenal glands that helps regulate sodium and potassium levels in the body. It promotes sodium reabsorption in the kidneys, which in turn leads to water retention and increased blood volume.

2. **Aldosterone Antagonists**:
- Aldosterone antagonists are medications that block the action of aldosterone. They are often used as diuretics to help reduce fluid retention in conditions like heart failure or hypertension.

3. **Effect of Aldosterone Antagonists**:
- When a patient is treated with an aldosterone antagonist, the reabsorption of sodium in the kidneys is inhibited. This leads to increased sodium excretion in urine.

4. **Consequences of Sodium Excretion**:
- Since sodium is being excreted, water will also be lost due to osmosis, leading to an increase in urine volume. Therefore, the urine volume is likely to increase, not fall.

5. **Impact on Blood Volume**:
- With decreased sodium reabsorption, there will be a decrease in water retention, which ultimately leads to a decrease in blood volume.

6. **Evaluating the Options**:
- Based on the above understanding:
- **Urine Volume**: Likely to increase (not the correct answer).
- **Plasma Potassium Concentration**: Likely to increase (not the correct answer).
- **Blood Viscosity**: Generally increases with higher blood volume (not the correct answer).
- **Blood Volume**: Likely to decrease (this is the correct answer).

7. **Conclusion**:
- Therefore, when a patient is treated with an aldosterone antagonist, there is likely to be a fall in **blood volume**.

### Final Answer:
When a patient is treated with an aldosterone antagonist, there is likely to be a fall in **blood volume**.

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