IgG
What it measures, and what changes the number.
Immunoglobulin G (IgG) is the most abundant antibody class in the blood and provides long-term protection after infections and vaccinations. This test measures total IgG in serum, not antibodies against a specific infection or food.
It is typically ordered in an immunoglobulin panel with IgA and IgM, and read alongside total protein and the gamma globulin fraction from protein electrophoresis, since IgG makes up most of that fraction. When more detail is needed, the four IgG subclasses may be measured separately.
Fasting is not usually required. Total IgG is measured by nephelometry or turbidimetry, and expected values vary with age and between methods. It should not be confused with pathogen-specific IgG serology or commercial food IgG panels, which are different tests. Labs may print it as IgG, Immunoglobulin G or Inmunoglobulina G.
Often read alongside: IgA, IgM, IgG subclass 1, Gamma globulin, Total protein