Definition
By Mayo Clinic staffMonoclonal gammopathy of undetermined significance (MGUS) is a condition in which an abnormal protein (monoclonal protein, or M protein) is in the blood. M protein is produced by plasma cells, a type of white blood cell. Monoclonal gammopathy of undetermined significance usually causes no problems. In some people, however, monoclonal gammopathy of undetermined significance is either associated with another disease or can progress over years to other disorders, including some forms of blood cancer.
Because it's difficult to predict whose condition will progress, if you have monoclonal gammopathy of undetermined significance you'll usually have annual checkups to monitor your level of M protein. If there's no increase in the protein, monoclonal gammopathy doesn't require treatment.
If monoclonal gammopathy of undetermined significance does progress, close monitoring leads to early diagnosis and treatment.
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- Rajkumar SV. Monoclonal gammopathy of undetermined significance. http://www.uptodate.com/home/index.html. Accessed Oct. 19, 2010.
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- Mikhael JR (expert opinion). Mayo Clinic, Scottsdale, Ariz. Nov. 12, 2010.


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