Highest level of LAP seen in ?

Ans. is 'a' i.e., Polycythemia veraLeukocyte alkaline phosphatase (LAP) score Alkaline phosphatase activity is found in the cytoplasm of neutrophils, osteoblasts, vascular endothelial cells, and some lymphocytes. Alkaline phosphatase level of peripheral blood neutrophils is quantified by the leukocyte alkaline phosphatase (LAP) score and is useful screening test to differentiate CML from leukamoid reaction and other myeloproliferative disorders.The LAP score is usually performed using the Kaplow procedure. The method uses a nephthal AS-BI phosphate as the substrate, which is coupled to fast violet '13' salt by the enzyme to produce a bright red reaction product that is visualized over neutrophilis.Normal LAP score ranges from 15-130. 0-13 is considered as low and > 130 is considered as high LAP score.