Acute Myelogenous Leukemia (AML)

Physicians perform an array of tests to help diagnose leukemia and determine its type and specific subtype. The tests help determine if there are changes in the amounts of different kinds of circulating blood cells, if the cells have an abnormal appearance when seen through a microscope, if there are changes in the cellular makeup of the bone marrow, to determine what changes have taken place in the genetic and molecular makeup of the diseased cells, and to discover any other factors that are helpful in deciding on the most effective course of treatment.

Blood Tests

Blood tests can show whether the amounts of various components of blood are within normal ranges. In leukemia, red blood cell levels may be low, causing anemia; platelet levels may be low, which can cause bleeding and bruising, and white blood cell levels may be diminished, leading to infections.

Bone Marrow Aspirates and Biopsies

Bone marrow aspirates and biopsiesare used to determine the number of blasts, or immature cells, in the marrow. Normally, blasts account for less than 5 percent of bone marrow content. In patients with leukemia, blasts increase to between 30 and 100 percent of marrow. In a bone marrow biopsy, physicians use a hollow needle inserted into the hip bone to remove a piece of marrow and bone for examination. In a bone marrow aspirate, a small sample of liquid bone marrow is withdrawn through a syringe.

Lumbar Puncture

If diseased cells are found through the bone marrow biopsy or aspirate, physicians will also perform a lumbar puncture, or spinal tap, to see if the disease has spread into the cerebrospinal fluid, which surrounds the central nervous system (CNS) -- the brain and spinal cord.

In addition, physicians use a number of tests that help them determine specific features of the cells in biopsied tissue including genetic abnormalities such as chromosomal rearrangements -- which are common in leukemias -- and whether the cells have specific proteins (antigens) on their surfaces; this information helps both identify the cells' origins and determine the patient's prognosis. These tests include the following:

• cytogenetic studies to determine chromosome changes in cells

• immunohistochemistry studies, in which antibodies are used to distinguish between types of cancer cells

• flow cytometry, in which prepared cells are passed through a laser beam for analysis

• molecular genetic studies, highly sensitive DNA and RNA tests to determine specific genetic traits of cancer cells.

Physicians sometimes use imaging tests to determine whether AML has affected the bones or the organs such as the kidneys or brain, or the lymph nodes. These tests can include chest x-rays, ultrasound, computed tomography (CT scan), and magnetic resonance imaging (MRI).