Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).

Assertion (A) : Total body fluid volume can be measured using antipyrine by dye dilution method.
Reason (R) : Antipyrine is hydrophilic in nature thus get distributed evenly in ICF and ECF both.

In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Remember the markers:
- Total Body Water (TBW): Lipophilic markers like Antipyrine, \(\text{D}_2\text{O}\), or Tritiated water (cross all membranes).
- Extracellular Fluid (ECF): Hydrophilic/polar markers like Inulin, Mannitol, or Thiosulfate (cannot cross cell membranes).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The indicator (dye) dilution method measures the volume of distinct body fluid compartments. The marker used must distribute uniformly throughout the target compartment without crossing into excluded spaces.

Step 2: Detailed Explanation:
1. Assertion (A): Total body water (TBW) includes both intracellular fluid (ICF) and extracellular fluid (ECF).
Antipyrine is an ideal marker used to measure Total Body Water using the indicator dilution method. Thus, Assertion (A) is true.
2. Reason (R): To distribute evenly across both ECF and ICF compartments, the marker must easily cross the capillary wall and the hydrophobic cell membrane.
Antipyrine is highly lipid-soluble (lipophilic), not hydrophilic. This lipid solubility allows it to readily pass through cell membranes and distribute uniformly throughout all body water compartments.
If a marker is highly hydrophilic (like inulin or mannitol), it cannot cross cell membranes and remains restricted to the ECF compartment. Thus, Reason (R) is false.

Step 3: Final Answer:
The correct option is 3, which corresponds to (A) is true but (R) is false.