Canterbury DHB


Management of MGUS - Information for general practitioners

MGUS (Monoclonal Gammopathy of Undetermined Significance)

Several disorders are associated with the presence of a monoclonal protein. These include Myeloma, Lymphoma, CLL and MGUS. The protein is most often IgG. Lymphoma will most often also present with enlarged lymph nodes. CLL will most often have an elevated lymphocyte count. Myeloma will often have a higher level of monoclonal protein as well as bone or kidney problems.

MGUS is the most common cause of a monoclonal protein (paraprotein) found when doing a serum protein electrophoresis (SPE) test. It is extremely common, found in 1% of people above 25 years, 3% above 70 years and up to 10% above 80 years of age. Other causes of a monoclonal protein (above) should be excluded by history, physical examination, full blood count (FBC) and biochemistry (creatinine and calcium). MGUS is asymptomatic and non-progressive and any significant symptom or rise in protein level should be cause for reassessment.

Approximately 1% of people with an MGUS progress to myeloma each year. The majority do not. By measuring the SFLC (Serum Free Light Chains), people can be further divided for their risk of progression:

Assess 3 factors:

paraprotein level > 15 g/L

1 point

abnormal SFLC ratio

1 point

non-IgG protein (i.e., IgA, IgM)

1 point

Number of factors

Risk of progression at 20 years

No abnormal factors


1 factor


2 factors


3 factors


Adapted from Rajkumar ASH education book 2005

For most people, follow up every 6-12 months will be adequate with history, examination, FBC, creatinine, calcium, SPE.

Reasons for referral:

About this Canterbury DHB document (26768):

Document Owner:

Amy Holmes (see Who's Who)

Last Reviewed:

September 2014

Next Review:

September 2016


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Topic Code: 26768