Which statement about LAP score in leukemoid reaction is true?

Which statement about LAP score in leukemoid reaction is true?

• A. Decreased
• B. Not used
• C. Increased
• D. Always normal

Answer: (C)

The key idea is that the leukocyte alkaline phosphatase (LAP) score differentiates reactive neutrophilia from malignant myeloproliferation. In a leukemoid reaction, neutrophils are activated by infection or inflammation, producing more LAP, so the LAP score rises. This contrasts with chronic myelogenous leukemia, where neutrophils typically have low LAP activity, leading to a low score. So the statement that the LAP score is increased in a leukemoid reaction is the correct interpretation. The other options don’t fit because LAP is used diagnostically to distinguish reactive from malignant conditions, and it is not characteristically decreased or always normal in leukemoid reactions.

The key idea is that the leukocyte alkaline phosphatase (LAP) score differentiates reactive neutrophilia from malignant myeloproliferation. In a leukemoid reaction, neutrophils are activated by infection or inflammation, producing more LAP, so the LAP score rises. This contrasts with chronic myelogenous leukemia, where neutrophils typically have low LAP activity, leading to a low score. So the statement that the LAP score is increased in a leukemoid reaction is the correct interpretation. The other options don’t fit because LAP is used diagnostically to distinguish reactive from malignant conditions, and it is not characteristically decreased or always normal in leukemoid reactions.