Question

Erythrocyte Sedimentation Rate is zero in

• A. Abetalipoproteinemia
• B. Afibrinogenemia
• C. Asplenia
• D. Aplastic anemia

Hint:

Think about what protein is needed for red cells to stack into rouleaux.

Answer 1

The Correct Option is B

Step 1: Understanding the Question.
We need to find the condition where the Erythrocyte Sedimentation Rate (ESR) actually falls to zero, not just low.

Step 2: Key Concept.
ESR measures how fast red cells settle in a tube over one hour. Red cells settle faster when they stick together in stacks called rouleaux. Rouleaux formation needs plasma proteins, mainly fibrinogen, which reduces the natural repulsion between red cells so they can clump. Without fibrinogen, rouleaux cannot form at all, and the red cells settle at their own very slow individual rate, giving an ESR close to zero.

Step 3: Detailed Explanation.
Option (A), abetalipoproteinemia, is a lipid disorder that produces acanthocytes (spiky red cells). These abnormal cells can lower ESR somewhat but do not make it zero.
Option (B), afibrinogenemia, is a rare disorder where fibrinogen is essentially absent from the plasma. Since fibrinogen is needed to form rouleaux, the ESR stays at zero no matter how much inflammation is present.
Option (C), asplenia, causes Howell Jolly bodies and target cells in the blood but does not remove fibrinogen, so ESR is usually normal or even raised, not zero.
Option (D), aplastic anemia, causes fewer red cells overall, which actually tends to raise ESR because there is less resistance to settling, not lower it to zero.

Step 4: Final Answer.
Only the complete absence of fibrinogen removes the ability of red cells to form rouleaux, giving a true zero ESR. \[ \boxed{\text{Afibrinogenemia}} \]