MGUS (Monoclonal Gammopathy)


Several disorders are associated with the presence of a monoclonal protein in the blood, including Multiple Myeloma, Lymphoma, Chronic Lymphocytic Leukaemia (CLL) and MGUS.

MGUS is defined by a low level of monoclonal protein (less than 30 g/L) and the absence of anaemia, hypercalcaemia, lytic bone lesions, and renal failure attributable to a plasma cell disorder or lymphoma. It is asymptomatic and very common; found in 3% of over 70 years, and up to 10% in over 80 years of age.

MGUS does not require treatment but there is a potential to progress to symptomatic multiple myeloma (MM) or lymphoma and therefore the condition needs long term clinical follow-up once detected.


Signs and Symptoms

If fever, malaise, bone pain, lymphadenopathy, hepatosplenomegaly, kidney problems, exclude significant causes of a monoclonal protein:

Multiple Myeloma

  • Patients may present with bone pain, lytic lesions in the bones, impaired renal function, hypercalcaemia, isolated normocytic anaemia, or pancytopenia
  • To diagnose, arrange the same tests as for MGUS. However, there will be higher levels of monoclonal protein plus other abnormalities, as above
  • Arrange urgent referral if there is associated spinal cord compression, hypercalcaemia, or renal failure
  • All require haematologist assessment and management


  • Assess for enlarged lymph nodes and/or hepatosplenomegaly. Cytopenias may also be present. If suspected refer for Haematology assessment


  • Associated with an elevated lymphocyte count. Manage according to the CLL pathway


  • May be associated with: Restrictive cardiomyopathy, unexplained gastrointestinal symptoms, peripheral neuropathy and carpal tunnel syndrome.

Risk of progression

Overall, approximately 1% of patients with MGUS progress to myeloma each year. Risk factors associated with a higher chance of progressing to symptomatic disease are listed below.

Assess 3 factors:
paraprotein level > 15 g/L 1 point
abnormal serum free light chain ratio 1 point
non-IgG protein (i.e., IgA, IgE) 1 point

Number of Factors Risk of progression at 20 years
No abnormal factors 5%
1 factor 21%
2 factors 37%
3 factors 58%

Adapted from Rajkumar et al, Blood. 2005;106(3):812-817.


Bloods - full blood count, creatinine, calcium, albumin, serum protein electrophoresis (SPE) with immunoglobulin levels, and urine Bence-Jones Protein (BJP).


MGUS can often be managed with regular monitoring through general practice. A suggested treatment algorithm is illustrated below. It is derived from the British Committee for Standards in Haematology guidelines 1.

Suggested algorithm for the investigation of newly detected M-protein


Referral Criteria

High Risk

  • Symptomatic of suspected myeloma or lymphoma
  • Abnormal physical signs suggestive of underlying myeloma or lymphoma
  • Unexplained abnormal investigation results (blood test or x-rays)
  • IgG paraprotein more than 15g/L
  • IgA paraprotein or IgM paraprotein more than 10g/L
  • Any IgD or IgE paraprotein irrespective of concentration

Low Risk, group who clinician is concerned with during primary care follow up

  • IgG paraprotein less than 15g/L
  • IgA paraprotein or IgM paraprotein less than 10g/L
  • Asymptomatic
  • No other abnormal results
  • BJP positive or negative
  • Uninvolved immunoglobulins low or normal

Referral Instructions

e-Referral Service Selection

  • Specialty: Haematology
  • Clinic Type: Not otherwise specified
  • Service: DRSS-Eastern-Haematology-Devon CCG- 15N

Referral Forms

DRSS Referral Form

Supporting Information

Pathway Group

This guideline has been signed off by NEW Devon CCG.

Publication date: July 2016


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