Sign in →

Test Code BLOD0615 Immunoglobulin M (IgM)

Useful For

  • Detecting acute infection.  IgM is the first specific antibody to appear in the serum after infection.  After the infection has subsided, IgM levels sink at a relatively rapid rate compared to IgG.
  • The differential diagnosis of acute and chronic infections by comparing specific IgM and IgG titers. If IgM is prevalent the infection is acute, whereas if IgG predominates the infection is chronic (e.g. rubella, viral hepatitis). 
  •  Increased polyclonal IgM levels are found in viral, bacterial, and parasitic infections, liver diseases, rheumatoid arthritis, scleroderma, cystic fibrosis and heroin addiction.  Monoclonal IgM is increased in Waldenström’s macroglobulinemia.
  • Increased loss of IgM is found in protein‑losing enteropathies and in burns.



Performing Laboratory

Bozeman Health Laboratory Services

Specimen Requirements

Specimen Type: Plasma or serum
Container/Tube: Light-green top (lithium heparin gel), red top, or gold top
Specimen Volume: 1 mL
Specimen Minimum Volume: 0.5 mL

Specimen Transport Temperature


Specimen Stability

Specimen Type Temperature Time
Plasma or Serum Ambient 2 months
  Refrigerated 4 months
  Frozen 6 months

Reference Values

Adults: 50-300 mg/dL


During childhood and adolescence, reference ranges for IgM are dependent on age and gender:


Age   IgM mg/dL
0-4 months   14-142 mg/dL
4 months-8 months   24-167 mg/dL
8 months-1 year Male 35-200 mg/dL
  Female 34-242 mg/dL
1 year-3 years Male 41-200 mg/dL
  Female 41-242 mg/dL
3 years-17 years Male 47-200 mg/dL
  Female 56-242 mg/dL
≥ 17 years   50-300 mg/dL


Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding