IgG subclass 4
What it measures, and what changes the number.
IgG subclass 4 is one of the four subtypes of immunoglobulin G, the main antibody class circulating in the blood. This test measures the IgG4 subtype separately. IgG4 is usually the smallest of the subclasses and is linked to long term or repeated exposure to certain antigens.
It is normally read alongside total IgG and the other subclasses, since the subclasses are interpreted as parts of the total. It is also sometimes ordered with IgE when allergic responses are being studied, and on its own when conditions involving IgG4 are being investigated.
No fasting is needed and the sample is ordinary serum. Results vary with the assay method and with age, and very high concentrations can affect some methods, so labs may dilute samples. Labs may print it as Inmunoglobulina G subclase 4.
Often read alongside: IgG, IgG subclass 1, IgG subclass 2, IgE