The presence of a high level of abnormal white cells in blood indicates the leukemia disease. Though the levels of white blood cells are high, because they are abnormal, they cannot perform its defense function, hence, the patient is more exposed to infections. The leukemia cells can migrate to different tissues and parts of body.
A simple blood test indicates the abnormal levels of white blood cells and the chages in shape of blood cells, but the doctor needs to perform several other tests to determine if the disease spread from bone marrow to the different regions throughout the body. Usually, bone marrow biopsy indicates the presence of abnormal leukemia cells and the CT scans and ultrasounds can indicate if leukemia spread throughout the body.