Monoclonal Gammopathy of Undetermined Significance (MGUS)

Monoclonal gammopathy of undetermined significance (MGUS) is a blood disorder that affects plasma cells in your bone marrow. Most of the time, M proteins don’t cause issues and most people with MGUS don’t have symptoms. Healthcare providers often discover this condition after taking blood or urine samples as part of a routine physical examination. Rarely, this condition may also become a blood cancer or a more serious blood disorder. Providers typically do blood and urine tests every six to 12 months to look for signs that monoclonal gammopathy of undetermined significance is becoming a more serious medical problem.

Who does it affect?

Monoclonal gammopathy of undetermined significance is more common in people age 50 and older. Your risk of developing it increases as you age. Starting at age 50, people have a 3% to 5% chance of developing this condition. People age 75 and older have a 5% chance. You may be more likely to develop MGUS if you are:

• Black.
• Male and designated male at birth (DMAB).
• Have a history of exposure to pesticides or insecticides.

How does this condition affect my body?

Monoclonal gammopathy of undetermined significance happens when your bone marrow produces abnormal plasma cells. Normally, individual plasma cells produce a specific type of antibody. Antibodies are special proteins that help identify and defend your body against germs.

In MGUS, abnormal plasma cells produce M proteins instead of antibodies. M proteins circulate in your bloodstream. These abnormal proteins may build up in your bloodstream and in your pee (urine), damaging your kidneys, heart and nerves. M proteins in your blood may also reduce your body’s ability to fight infection.

Is MGUS a cancer?

No, it’s not cancer but it can become cancer. Studies show that 20% of people with this condition develop multiple myeloma. Other people with monoclonal gammopathy of undetermined significance may develop other blood cancers or blood disorders:

• Amyloidosis.
• Waldenstrom macroglobulinemia.
• Chronic lymphocytic leukemia.