TAM (Treatments and Medicines) NHS HighlandUsually found incidentally on immunoglobulin testing whilst assessing some form of clinical problem in a patient.
Monoclonal gammopathy of uncertain significance (MGUS) (Guidelines)
Warning
Audience
- HHSCP
- Primary and Secondary Care
- Adults only
With age, MGUS is an increasingly prevalent condition (up to 2% in people in sixth decade, up to 4% in seventh decade, 5% in eighth decade and so on). MGUS patients are usually identified by General Practitioners, often incidentally. It should be noted that co-incidental back pain is common too.
MGUS only infrequently leads to the development of a haematological disorder, most commonly a lymphoproliferative disorder but sometimes myeloma or amyloidosis. Only 20% of all such patients progress if followed over 20 years. Additionally only a small proportion of such patients develop disorders that may be linked to the presence of a paraprotein (eg, light chain deposition in kidneys or amyloidosis)
Thus, most likely MGUS patients do not need extensive or invasive investigation, but some will (see below).
MGUS only rarely requires treatment but does require periodic monitoring in the community, often alongside monitoring being undertaken for other conditions the patients may have.
Click here for a Myeloma UK: GP guide booklet
First assessment
In addition to the immunoglobulin result, ensure that ‘free light chain’ testing is performed (liaise with immunology laboratory- results take about 2 weeks to be returned).
MGUS patients can then be risk stratified to help decide on the need for secondary care referral and the frequency of follow up. Use: MGUS Prognosis | QxMD
- 'Low' & 'Low-intermediate' risk patients: merely need annual follow up in primary care
- 'High-intermediate' and 'High' risk patients: should be referred for assessment (not as ‘USC’).
- If then assessed as only having an MGUS, these patients need 6 monthly tests back in primary care.
Follow up
In addition to basic FBC, U&E, LFT and Calcium assessments, the patient should also have their paraprotein checked as below:
- For patients with intact paraproteins (eg, IgM, IgG, IgA etc): Request immunoglobulin quantitation (brown tube to immunology laboratory)
- For patients with light chain only paraproteins: Request Free light quantitation (brown tube to immunology laboratory)
NB: Please do NOT send copies of results to the Haematology Department.
Frequency of follow up
- 'Low' & 'Low-intermediate' risk patients: merely need annual follow up
- 'High-intermediate' and 'High' risk patients: should be tested 6 monthly.
Criteria for referral of follow up patients to Haematology Department
MGUS patients should be referred to the haematology department if the patient is developing clearly progressive symptoms and physical signs to suggest the development of lymphoma or myeloma.
The need to refer would be supported by development of progressive paraproteinaemia (see below), progressive significant cytopenias, progressive lymphocytosis or sustained hypercalcaemia.
- For IgG/IgA/IgM cases: If the patient’s paraprotein rises above 20g/L even in the absence of the above issues.
- For light chain only cases: If the patient’s free Kappa: Lambda light chain ratio is greater than 8 or less than 0.125.
Criteria for referral to other departments
- If the patient develops issues such as peripheral neuropathy or carpal tunnel syndrome then refer for assessment to the neurology department for assessment as to the presence of a paraprotein related neuropathy or amyloidosis.
- If the patient develops cardiac dysfunction then the patient should be referred to the cardiologists to be assessed for evidence of cardiac amyloidosis.
- If the patient develops progressive renal dysfunction or proteinuria then nephrology investigation is required to see if the deterioration is linked to the paraprotein.
| Abbreviation | Meaning |
| USC | Urgent suspected cancer |