There is no fixed value for the exact rate of positive NAP staining. The reference value varies from hospital to hospital, so when performing the analysis, you need to go to the hospital where the test is performed for it to be meaningful. Neutrophil alkaline phosphatase, or NAP, is a non-specific hydrolase released by its cytoplasmic special granules that catalyzes the hydrolysis of monophosphate esters of various alcohols and phenols under alkaline conditions.NAP is mainly found in neutrophils at the maturation stage, while other components such as acidophilic, basophilic, lymphoid, monocytes and megakaryocytes, platelets, plasma cells, etc., are all negative. NAP viability reflects the maturity and function of mature granulocytes, and the enzyme activity gradually increases as the cells mature. NAP positivity increases with neutrophil activation. In pathological conditions, changes in NAP activity often help in the diagnosis and differential diagnosis of certain diseases. NAP staining positivity that is relatively high may be due to inflammation, and it is recommended that treatment and retesting be done as soon as possible.