When physicians suspect that a patient may have acute myeloid leukemia (AML), they first will obtain a detailed medical history and perform a complete physical examination. During the physical examination, the physician will examine the lymph nodes, spleen and liver for swelling.

Next, a variety of tests may be ordered to diagnose, classify, and monitor the leukemia.  Samples of cells from the patient’s blood and bone marrow will be examined to verify the diagnosis. Additional tissue and cell samples may also be needed to guide treatment.

Common tests that can help diagnose AML include:

• Complete blood count and blood smear. A complete blood count (CBC) is a blood test that measures the number of red blood cells, white blood cells and platelets in a sample of blood. A CBC also measures the amount of hemoglobin in the red blood cells and a number of other factors. A blood smear is the examination of cells under a microscope. Changes in the numbers of different blood cell types and the appearance of the cells can suggest leukemia. Patients with AML usually have too many white blood cells and many of the cells will be blasts, an immature blood-forming cell usually found only in the bone marrow. Many patients may have too few red blood cells and platelets as well.
  
  
• Bone marrow aspiration and biopsy.  Although other tests may suggest AML, the diagnosis usually cannot be verified without examining a sample of bone marrow cells. A bone marrow aspiration involves using a needle to collect a small sample of liquid bone marrow. A bone marrow biopsy uses a larger needle to remove a core of bone marrow.  Usually performed at the same time, these procedures may be ordered to determine if leukemia is present or to monitor treatment.
  
  
• Blood chemistry tests. These tests measure the level of specific chemicals in the blood. They are used to monitor changes in organ function caused by the leukemia or the treatment with certain chemotherapy drugs. The tests may be ordered to determine whether treatment is required to correct abnormalities.

Additional tests include laboratory tests to diagnose and classify the leukemia. These include:

• Routine microscopic exam. All samples (bone marrow, lymph node tissue, blood and cerebrospinal fluid) are studied under a microscope by a pathologist. A number of characteristics, including the size, shape and maturity of the cells are noted in order to classify the cancer cells into specific types.  The test also may be ordered to determine if a patient is in remission.
  
  Blasts are the most immature type of cell. The amount of cells in the bone marrow that are blasts will be determined for diagnosis of AML. Blasts may contain a chromosome change that is specific for a type of AML. Following treatment, a patient must have a blast percentage of 5 percent or less to be considered in remission.
  
  
• Flow cytometry and immunophenotyping. This procedure detects certain molecules on the surface of leukemia cells. This is a very accurate test for determining the exact type of leukemia present in a patient.
  
  
• Cytogenetics. This test uses a microscope to evaluate the chromosomal characteristics of cells. It may be ordered to determine if the cells have too many chromosomes, or if the chromosomes have any abnormalities. The testing usually takes up to 3 weeks because the leukemia cells must grow in a laboratory before the chromosomes can be analyzed. Certain chromosomal abnormalities have been identified in AML cells and their presence or absence may help in predicting a patient's prognosis.
  
  
• Molecular genetic studies. These tests are more sensitive in examining leukemia cell DNA for precise abnormalities.  Molecular genetic studies are useful in classifying AML because many of its subtypes have translocations that are too small to be detected with a microscope. Information about the translocations can be used to predict the patient’s response to treatment and detect remaining cancer cells following treatment. 

AML rarely forms visible tumors. For that reason, imaging tests have limited value. If imaging tests are performed on patients with AML, they are usually conducted to diagnose infections or other leukemia-related problems. Imaging tests that may be ordered include chest x-ray, computed tomography (CT) scan, magnetic resonance imaging (MRI), gallium scan, bone scan and ultrasound. The imaging tests may be used to detect enlarged organs or lymph nodes, large collections of leukemia cells and sites of infection.