Which statement about LAP score in leukemoid reaction is true?

Which statement about LAP score in leukemoid reaction is true?

• A. LAP score is not used
• B. LAP score cannot be determined
• C. LAP score helps differentiate from CML by being increased
• D. LAP score is always decreased

Answer: (C)

The key idea here is how the LAP score behaves in neutrophil-dense reactions and what that means diagnostically. In a leukemoid reaction, neutrophils are activated and release more alkaline phosphatase, so the LAP score goes up. In chronic myeloid leukemia, these neutrophils have intrinsically lower LAP activity, so the score is typically low. This difference helps clinicians tell reactive neutrophilia from CML when there is marked neutrophilia. So the statement that LAP score helps differentiate from CML by being increased is the correct one. The other options don’t fit: LAP can be measured and is often elevated in leukemoid reactions, not always decreased, and it’s not a non-useful test.

The key idea here is how the LAP score behaves in neutrophil-dense reactions and what that means diagnostically. In a leukemoid reaction, neutrophils are activated and release more alkaline phosphatase, so the LAP score goes up. In chronic myeloid leukemia, these neutrophils have intrinsically lower LAP activity, so the score is typically low. This difference helps clinicians tell reactive neutrophilia from CML when there is marked neutrophilia. So the statement that LAP score helps differentiate from CML by being increased is the correct one. The other options don’t fit: LAP can be measured and is often elevated in leukemoid reactions, not always decreased, and it’s not a non-useful test.