It's not clear what causes myeloma.
Doctors know that myeloma begins with one abnormal plasma cell in your bone marrow. The abnormal cell multiplies rapidly.
In the bone marrow, myeloma cells crowd out healthy white blood cells and red blood cells, leading to fatigue and an inability to fight infections.
The myeloma cells continue trying to produce antibodies, as healthy plasma cells do, but the myeloma cells produce abnormal antibodies that the body can't use. Instead, the abnormal antibodies (monoclonal proteins, or M proteins) build up in the body and cause problems such as damage to the kidneys. Cancer cells can also cause damage to the bones that increases the risk of broken bones.
Key word: causes multiple myeloma cancer