Synonyms: Total IgM
Related tests: serum electrophoresis, urine electrophoresis, kappa light chains and lambda light chains, IgG, IgA
Clinical significance
Class M immunoglobulins are the first antibodies to appear in response to an antigenic stimulus and are later replaced over time by IgG antibodies.
IgM does not cross the placenta, so high IgM levels in cord blood (or in the first week of life) suggest an infection before birth.
Waldenström’s macroglobulinaemia is characterised by the presence of a monoclonal IgM immunoglobulin.
Clinical indications
Further investigation when a monoclonal component is found on electrophoresis.
Sample type
The patient must have a blood sample taken.
Preparation
You must fast for at least 8 hours; a small amount of water is allowed. You must have been standing or sitting upright for at least 30 minutes.
Notes