Is defined as a disproportionate increase in plasma volume as compared to the synthesis of new red blood cells. a. Hyponatremia b. Dehydration c. Hemodilution d. Atrophy
The correct answer and explanation is:
The correct answer is c. Hemodilution.
Explanation:
Hemodilution refers to the relative decrease in the concentration of red blood cells (RBCs) in the blood due to an increase in plasma volume. In simpler terms, it means that the blood becomes more “diluted” because there is more fluid (plasma) compared to the number of red blood cells.
- Normally, the blood volume consists of plasma (the liquid part) and the cellular components (mainly red blood cells, white blood cells, and platelets).
- When plasma volume increases disproportionately—such as through excessive fluid intake, intravenous fluids, or certain pathological states—the concentration of RBCs in the blood decreases if there isn’t a corresponding increase in red blood cell production.
- This causes a condition known as hemodilution, which can lower the hematocrit (the percentage of blood volume occupied by RBCs) and hemoglobin concentration, even if the absolute number of RBCs remains the same.
Why is this important?
- Hemodilution can occur in several clinical situations, such as pregnancy, intravenous fluid administration, or conditions causing fluid retention (like heart failure or kidney disease).
- It is different from anemia, where the actual number of RBCs decreases due to impaired production or increased destruction.
- Hemodilution is a volume-related change, not a production-related problem.
Why the other options are incorrect:
- a. Hyponatremia: This is a low concentration of sodium in the blood, often caused by excessive water retention or loss of sodium. It does not specifically describe plasma volume changes relative to RBCs.
- b. Dehydration: This is a loss of body water, causing decreased plasma volume and often a relative increase in the concentration of RBCs (hemoconcentration), the opposite of hemodilution.
- d. Atrophy: This means a reduction in size or wasting away of an organ or tissue, unrelated to plasma volume or red blood cell synthesis.
Summary
Hemodilution is defined as a disproportionate increase in plasma volume compared to the synthesis of new red blood cells, leading to diluted blood with fewer RBCs per unit volume. This can impact oxygen delivery and blood test results and is important to recognize in clinical practice.