What is monoclonal protein?

Monoclonal protein, or 'M protein,' is an abnormal protein produced by plasma cells in bone marrow, according to the Mayo Clinic. The presence of such protein in the blood refers to a condition known as monoclonal gammopathy of undetermined significance (MGUS).

In the majority of cases, MGUS is not harmful and carries no side effects. Too much accumulation, however, may cause damage to other body tissues and progress to other disorders, including blood cancer, cites Mayo Clinic.

Those testing positive for M protein are encouraged to schedule periodic checkups to monitor protein levels; in most instances, no further treatment is required.