Immunoglobulin M (IgM)
- Fresh serum of the patient is needed.
- Analyze the sample as soon as possible or can store at 4 °C for a few hours (less than 72 hours).
- The sample is stable at -20 °C for 6 months.
- Used to detect monoclonal gammopathy.
- It is advised in immune deficiencies.
- IgM exists in two form
- Monomeric IgM form exists as a B- cell receptor for antigen.
- Pentameric IgM form is present in the blood. These five basic units are joined by the J-chain.
- It is 10 % of the total immunoglobulin with a molecular weight of 900,000 and is 19 S.
- Its concentration is 120 mg/dl.
- Its molecular weight is 900,000 and 19S.
- There are 10 potential sites for antigen binding.
- IgM is the first antibody production in response to antigenic stimulation called Primary immune response.
- In primary response, there is the stimulation of B-Lymphocytes which form the plasma cells and produce IgM.
- IgM as a pentamer form is the most effective stimulator of the complement system for a lytic reaction.
- In fetal life, this is the first immunoglobulin which appears first and its raised level in neonate indicates intrauterine infection.
- IgM has a half-life of 10 days.
- It is predominantly present in the intravascular spaces.
- It is a poor toxin neutralizing antibody.
|one month||20 to 80|
|2 to 5 month||25 to 100|
|6 to 9 month||35 to 125|
|10 to 12 month||40 to 150|
|1 to 8 year||45 to 200|
|9 to 12 year||50 to 250|
|>12 year||50 to 300|
- To convert into SI unit x 10 = mg/L
- Adult = 55 to 375 mg/dL
- Children = 20 to 200 mg/dL
- 0 to <5 months = 26 to 122 mg/d
- 15 to <24 months = 46 to 152 mg/dL
- 2 to <4 years = 37 to 184 mg/d
- 10 to <13 years = 41 to 255 mg/dL
- 16 to <18 years = 49 to 201 mg/dL
- More than 18 years = 37 to 286 mg/dL
- Values vary from different methodology.
Decreased level of IgM seen in:
- Decreased level seen in congenital deficiency diseases.
Increased level of IgM seen in :
- Elevations of IgM may be due to polyclonal immunoglobulin production which was seen in various infections.
- An isolated increase in IgM level may be seen in viral infections e.g. Viral hepatitis, infectious mononucleosis, and early response to bacterial or parasitic infection.
- Increased levels of IgM may be seen in Rheumatoid arthritis, biliary cirrhosis, and some other chronic disorders.
- Raised levels are also seen in Hyper IgM dysgammaglobulinemia, active sarcoidosis, collagen vascular diseases, nephrotic syndrome.
- Monoclonal raised levels are seen in :
- Waldenstrom’s globulinemia.