Leukemoid reaction with polycythemia vera is associated with which LAP score?

Leukemoid reaction with polycythemia vera is associated with which LAP score?

• A. Normal
• B. Decreased
• C. Not measurable
• D. Increased

Answer: (D)

LAP stands for leukocyte alkaline phosphatase and helps distinguish reactive leukocytosis from leukemia. In a leukemoid reaction, neutrophils are highly active and contain more alkaline phosphatase, so the LAP score is elevated. When polycythemia vera is associated with a leukemoid-like process, the neutrophils remain activated, keeping the LAP high. That is why the increased LAP option best fits. A normal or decreased LAP would point away from a reactive leukocytosis, and not measurable is not typical of a true reactive process.

LAP stands for leukocyte alkaline phosphatase and helps distinguish reactive leukocytosis from leukemia. In a leukemoid reaction, neutrophils are highly active and contain more alkaline phosphatase, so the LAP score is elevated. When polycythemia vera is associated with a leukemoid-like process, the neutrophils remain activated, keeping the LAP high. That is why the increased LAP option best fits. A normal or decreased LAP would point away from a reactive leukocytosis, and not measurable is not typical of a true reactive process.