MGUS and Myeloma encompass a wide spectrum of problems from an incidental finding that will be of no consequence to the patient and is very common (eg a small MGUS paraprotein in an elderly patient) to a life threatening emergency that requires treatment as soon as possible (eg myeloma with cord compression or acute renal failure).


Bone pain



Hypercalcaemia( confusion, muscle weakness, constipation, thirst, polyuria)

Recurrent infection

Hyperviscosity symtpoms ( headache, SOB, visual disturbance, cognitive impairment)

Spinal cord compression


Primary care Investigations:

There is no single diagnostic test. Plain xrays do not detect all myelomatous bone lesions.

Bloods: FBC, Immunoglobulins, Protein Electrophoresis, Bone profile, U&E,

Urine: Bence Jones protein

When associated with neoplasia, IgM paraproteins are usually associated with a low grade lymphoma (so assess for lymphadenopathy/organomegaly) whereas IgG/IgA paraproteins and serum light chains/urinary BJP tend to be associated with myeloma, but there is cross over.

If you are uncertain about the interpretation of an electrophoresis result, or have clinical concerns about a patient awaiting an electrophoresis result contact Haematology via their Advice and guidance service: rch-tr.haematologyreferrals@nhs.net

Please note where a paraprotein number is referred to this is the size of the paraprotein itself (the serum protein electrophoresis result) not the total IgG/IgA/IgM


When to refer as 2 week wait to haematology:

If you are concerned that the patient has myeloma, for example: –

  1. Presence of unexplained anaemia/renal failure/hypercalcaemia/excess infection/bone pain, or lytic lesions/vertebral collapse that is not typical of osteoporosis (eg younger man)


  1. A paraprotein (if you are very concerned you do not need to wait for the full result please discuss with the on call haematologist on basis of the initial results) or immuneparesis (some patients do not have a paraprotein but may have low IgG/IgA/IgM) or positive BJP/SFLC result.

If concerns about acute renal failure, cord compression or hyperviscosity speak to the on call haematology consultant via switchboard.


When to consider routine referral to haematology via Choose and Book:

IgG paraprotein >15g/L or

IgA paraprotein >10g/L or

IgM paraprotein >10g/L or

Kappa light chain >300mg/L or

Lambda light chain >300mg/L or

Kappa/lambda ratio <0.01 or

Kappa/lambda ratio >100

in any age group where further investigation is considered appropriate

The following may also be appropriate to be seen routinely in clinic:

  • Younger (<60 years) or more anxious patient with a paraprotein that would like further investigation and follow up via the MGUS distance clinic rather than in the community


  • A paraprotein plus any concerning features (eg anaemia, renal failure, bone pain, infection) that require further investigation, but are stable and not urgent


  • If the paraprotein level increases by more than 25% in 6 months during monitoring (a minimum absolute increase of 5g/l)


Who to monitor in primary care?

If a patient has a paraprotein /light chains  below the levels stated above  andthere is no evidence of end organ damage (no unexplained anaemia, renal impairment, hypercalcaemia, unexplained bony lesions, organomegaly or lymphadenopathy) then their MGUS can be monitored in the community. 


MGUS community follow up

Please note where a paraprotein number is referred to this is the size of the paraprotein itself (the serum protein electrophoresis result) not the total IgG/IgA/IgM

If a patient has either:

an IgG paraprotein <15g/l or

  • an IgA paraprotein <10g/l or
  • kappa light chain >300mg/l or
  • lambda light chain >300mg/l or
  • kappa/lambda ratio <0.01 or
  • kappa/lambda ratio >100 or
  • an IgM paraprotein <15g/l

and there is no evidence of end organ damage -  no unexplained anaemia

                  no renal impairment

                  no hypercalcaemia

                  no unexplained bony lesions

                  no organomegaly or lymphadenopathy

then it is reasonable for their MGUS to be monitored in the community.


FBC, U&E, Ca, Protein Electrophoresis, (if the BJP or serum free light chains were positive also request serum free light chains)  initially repeat in 3 months and if stable monitor 6-12 monthly thereafter.

Paraproteins usually increase in size with time. There is no set number at which they become a specific concern if the patient is otherwise well and there are no other concerns.

As patients become frailer, or have a limited prognosis due to their other conditions, you may wish to take a pragmatic decision not to continue to monitor their paraprotein especially if it is small or has been stable for a long period of time.

 Consider routine referral to Haematology (either A&G or C&B) if:

  •  IgG or IgM paraprotein has risen to >20g/l
  •  IgA to >15g/l
  • kappa or lambda light chain >300mg/l
  • kappa/lambda ratio <0.01 or >100
  • if the paraprotein level increases by more than 25% in 6 months  (with minimum absolute increase of 5g/l) then you might wish to refer to the haematology OPD or take advice.

If develops symptoms suspicious of myeloma REFER 2WW HAEMATOLOGY

Patient information:

MGUS patient information: http://www.macmillan.org.uk/information-and-support/diagnosing/causes-and-risk-factors/pre-cancerous-conditions/mgus.html


Dr Elizabeth Parkins, Consultant Haematologist, RCHT

Dr Adam Forbes, Consultant Haematologist, RCHT

Dr Bridgitte Wesson, GP & Kernow RMS Haematology guideline lead


Review date: 13/09/2020

Next Review date: 13/09/2021