Topics:
Animal Physiology, Animal Refresher
Use of Inulin in Physiology
Inulin is used to measure:
- Both ECF and GFR — Correct Answer
- Plasma volume only
- ECF only
- GFR only
Explanation:
Correct Answer: Both ECF and GFR
Inulin is a plant-derived polysaccharide used as a physiological marker to measure two important parameters:
Why Inulin is Ideal as a Marker
- It distributes only in extracellular fluid (ECF) — does not enter cells.
- It is freely filtered at the glomerulus.
- It is neither secreted nor reabsorbed by kidney tubules → clearance = GFR.
- It is not metabolized by the body.
Measurement Summary
| What is Measured | Substance Used |
|---|---|
| Total body water (TBW) | Heavy water (D₂O) or Tritiated water (³H₂O) |
| Extracellular fluid (ECF) & GFR | Inulin |
| Plasma volume (PV) | Evans blue dye (T-1824) |
| ICF | Calculated: TBW − ECF (cannot be measured directly) |
Why Other Options Are Wrong
- Plasma volume only → Plasma volume is measured by Evans blue dye, not inulin.
- ECF only / GFR only → Inulin measures BOTH ECF and GFR; selecting either alone is incomplete.
📚 About this Topic — Animal Physiology
This multiple choice question is from Animal Physiology, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Physiology to strengthen your preparation.
