Why Is a Bone Marrow Test Performed?

Technician preparing bone marrow transplant. Credit: Chris Minerva / Getty Images

A bone marrow biopsy may be performed to diagnose and monitor diseases, conditions and cancers that affect the blood-forming cells and immune system cells of the body - white blood cells, red blood cells, and platelets. It is also performed before and after treatment for these conditions and bone marrow or stem cell transplants.

Why Must the Bone Marrow Be Tested?

The bone marrow exam is only done when the complete blood count (CBC) and other tests are abnormal. The CBC can give a picture of what might be happening inside the bone marrow, but it is only a clue. Disordered and cancerous cells in the marrow may not circulate in the bloodstream in large enough numbers to be detected. To see what is really going on the marrow, they need to take a sample of the marrow and look at it in the lab.

What Is in the Bone Marrow?

Your bone marrow is where your body produces blood cells. It is where the stem cells live. In normal bone marrow, a portion of the stem cells differentiate and specialize to produce different types of blood cells: red blood cells, white blood cells, and platelets.

Any of these types of marrow cells can become disordered. They may become cancerous and reproduce at a rate that crowds out the normal cells. They may be stuck at an earlier stage of maturation, so they don't form functional blood cells. One or more of the cell lines may be reduced, leading to anemia. Some cancers first develop outside of the marrow and then infiltrate the bone marrow.

Common Reasons Why a Bone Marrow Biopsy Test Is Performed

  • Detecting bone marrow involvement by a cancer - many cancers, notably lymphomas spread from their primary site to different organs of the body, including the bone marrow. A bone marrow test can tell whether cancer has spread to the marrow. This is important in staging for lymphoma, breast cancer and lung cancer.
  • Detecting cancers of the blood - blood cancers or leukemias are diagnosed mainly by detecting cancer cells in the marrow. A bone marrow biopsy will identify which cells are producing the leukemia, which is important for prognosis and treatment.
  • Finding the cause of anemia, high and low blood cell counts - When your CBC counts are low or high for WBC, RBC or platelets without a known reason, the biopsy will help identify the cause.
  • Bone marrow infiltration by other diseases - certain infections and metabolic disorders may infiltrate the bone marrow. A bone marrow test can help diagnosing such disorders.
  • Monitoring bone marrow suppression and recovery in cancer treatment: If you have had chemotherapy or radiation for blood cancer or other cancers, a bone marrow biopsy may be needed to see how it is affecting your marrow.
  • Monitoring stem cell and bone marrow transplants: After a bone marrow or stem cell transplant, a biopsy may be done to see if it has been successful and to monitor for recurrence of your disease.
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