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Monoclonal Gammopathy of Unknown Significance (MGUS)


  • This manual is not a substitute for consultation with an appropriate specialist.
  • The contents of this manual have been developed through consensus of a Provincial Tumour Group. Please note the various update dates for each section as some of the content of the manual may not be up to date.

1. Diagnosis

Updated 28 July 2008

All of these must be present:​

  • Serum monoclonal paraprotein
  • No lytic bone lesions
  • Bone marrow plasma cell proportion less than 10%

Usually the paraprotein type is IgG or IgA and the level is less than 30 g/L and the levels of the uninvolved immunoglobulins are normal, however, in up to 25% of cases of MGUS one or more of the uninvolved immunoglobulins may be below normal.​

2. Staging

No staging system has been devised for MGUS. Initial evaluation should include all the same tests as for multiple myeloma.

3. Treatment

Patients with MGUS do not require any treatment, unless they develop lesions or syndromes attributable to the paraprotein, such as peripheral neuropathy, amyloidosis or renal dysfunction. It is quite rare for such complications to be seen with MGUS. Such findings usually indicate that myeloma is actually present and will eventually manifest itself.

4. Follow-up

Patients with MGUS are at risk to develop lymphoproliferative diseases such as myeloma or malignant lymphoma. They should be re-examined annually and at those times the following tests should be obtained:

  • CBC, serum creatinine, calcium
  • Serum and 24 h urine protein electrophoreses
  • Skeletal survey (optional after 3-5 years of observation with no evidence of progression)​​​​
SOURCE: Monoclonal Gammopathy of Unknown Significance (MGUS) ( )
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