IgM
What it measures, and what changes the number.
IgM, or immunoglobulin M, is a large antibody that the immune system typically produces first when it meets a new infection or antigen. This test measures the total amount of IgM in the blood, not antibodies against any one specific germ.
It is commonly ordered together with IgG and IgA as a basic immunoglobulin panel, because the three classes are read in relation to each other. It may also be reviewed next to serum protein electrophoresis results such as the gamma globulin fraction and total protein.
The sample is serum and fasting is not usually required. Results are produced by nephelometry or turbidimetry and can differ slightly between methods, and values change with age, especially in childhood. Labs may print it as Inmunoglobulina M.
Often read alongside: IgG, IgA, IgE, Gamma globulin, Total protein