Leukemia cannot be detected by routine blood tests alone. If leukemia is suspected, further tests such as bone marrow, genetic and chromosomal tests are required to make a definite diagnosis. If there is a drop in red blood cell and platelet counts in routine blood tests, it suggests the possibility of bone marrow suppression, which in some of these patients is due to leukemia. A sudden increase in the number of white blood cells, well above the normal range of 4000-10000/μL, may indicate the presence of leukemia, but may also be due to inflammatory conditions such as pneumonia or acute suppurative tonsillitis. Acute promyelocytic leukemia, on the other hand, has a white blood cell count that is well below the normal range. Therefore, it is difficult to conclude the presence of leukemia in a patient based on routine blood results alone, and further testing is required. Bone marrow biopsy is required for suspected leukemia, which is generally painless and can basically clarify the presence or absence of leukemia after the operation through local anesthesia. Therefore, routine blood tests are only one of the very basic blood tests. If there are problems with routine blood tests, they need to be combined with other tests to confirm the specific disease and cannot directly conclude that there is a risk of leukemia.