Definition
- IgM is the first antibody to appear in response to antigen. It can be produced by the fetus and cannot be crossed by the placenta.
- Normal range: see Table 16.44.
TABLE 16 " 44Normal Ranges for IgM by AgeView LargeTABLE 16 " 44Normal Ranges for IgM by Age Age Range (mg/dL) 0 " 30 d 0 " 24 1 mo 19 " 83 2 mo 16 " 100 3 mo 23 " 85 4 mo 26 " 96 5 mo 31 " 103 6 mo 33 " 97 7 " 8 mo 32 " 120 9 " 11 mo 39 " 142 1 y 41 " 164 2 y 46 " 160 3 y 45 " 190 4 y 41 " 186 5 " 7 y 46 " 197 8 " 9 y 49 " 230 ≥10 y 60 " 263
Use
- Diagnosis of hereditary and acquired IgM immunodeficiencies
- Diagnosis of Waldenstr śm macroglobulinemia
- Earliest Ig serologic diagnosis of infectious disease
Interpretation
Increased In
- Polyclonal
- Liver disease
- Chronic infections
- Secondary to nephritic syndrome
- Hyper IgM syndrome
- Monoclonal
- Waldenstr śm macroglobulinemia
- Lymphoma
- CLL
- Multiple myeloma (rare)
- Schnitzler syndrome
- Cold IgM antibody agglutinin
- MGUS
Decreased In
- Protein-losing syndromes
- Non-IgM myeloma
- Infancy, early childhood
Limitations
- Selective deficiency of IgM is a rare immune disorder in association with infection and normal levels of other immunoglobulin isotypes.