A patient presented with headache and fever. His investigations revealed hemoglobin of 16g/dl, TLC of 21,000/ uL, platelet count of 3,75,000. His DLC showed Neutrophils (25%), Lymphocytes (20%), Metamyelocytes and myelocytes 40%and eosinophils5%. Which of the following is the next best investigation in this patient?

In the above question, lab investigation of the patient reveals normal hemoglobin, Elevated TLC, normal platelet count, decreased Neutrophils, Elevated metamyelocytes and myelocytes. This lab picture clearly indicates that immature WBC's are much more in number than the mature WBC'S. Such a condition is given the name "shift to the left". This is seen in association with two types of conditions: 1.) Leukemoid reaction 2.) CML To distinguish between the two condition, we can do: LAP score (not commonly performed now). - CML- decreased, Leukemoid reaction- increased. Philadelphia chromosome presence (confirmatory test)- CML- Philadelphia chromosome (+ve), Leukemoid reaction - Philadelphia chromosome(-ve) .