serum immunoglobulin measurement blood immunoglobulin M level serum immunoglobulin M level 2014-01-27T12:35:25Z CMO:0002104 CMO:0002110 EFO:0004993 The amount in a specified sample of serum of one or more types of immunoglobulin M (IgM), one of the five classes of antibodies produced by the body. IgM is found in circulating body fluids and is the first class of antibodies to appear in response to an initial exposure to an antigen. clinical_measurement_ontology jsmith serum IgM level serum IgM measurement serum total IgM level serum total immunoglobulin M level