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The rubella IgG test is a serological test carried out with the aim of verifying whether a person has immunity against the rubella virus or is infected with this virus. This test is mainly requested during pregnancy, as part of prenatal care, and is usually accompanied by the IgM dosage for rubella, so that it is possible to know if there is, in fact, a recent or old infection or immunity.
Although it is normally indicated in prenatal care due to the risk of the woman passing the virus to the baby during pregnancy if infected, the IgG test for rubella can be requested for all people, especially if they have any A sign or symptom indicative of rubella such as a high fever, headache, and itchy red patches of skin.Know how to identify the symptoms and rubella.
What does IgG reagent mean
When the exam indicates IgG reagent for rubella, it means that the person has antibodies against the virus, which is probably due to the rubella vaccine, which is part of the schedule of vaccination and the first dose is recommended at 12 months of age.
Reference values for rubella IgG may vary by laboratory, however, in general, the values are:
- Non-reactive or negative, when the value is less than 10 IU/mL;
- Undetermined, when the value is between 10 and 15 IU/mL;
- Reagent or positive, when the value is greater than 15 IU/mL.
Although in most cases the rubella IgG reactive is due to vaccination, this value can also be reactive due to recent or old infection and, therefore, it is important that other tests are done to confirm the result.
How the exam is done
The IgG test for rubella is simple and does not require any preparation.
Sample analysis is performed using serological techniques to identify the amount of IgG antibodies circulating in the blood, thus making it possible to know if there is a recent or old infection or immunity.
In addition to the IgG test, the dosage of the IgM antibody against rubella is also carried out so that it is possible to verify the person's immunity against this virus. So the possible exam results are:
- Reactive IgG and non-reactive IgM: indicates that there are antibodies circulating in the body against rubella virus that were produced as a consequence of vaccination or past infection;
- Reactive IgG and Reactive IgM: indicates recent active infection;
- Non-reactive IgG and non-reactive IgM: indicates that the person has never come into contact with the virus;
- Nonreactive IgG and Reactive IgM: indicates that the person has or has had an acute infection for a few days.
IgG and IgM are antibodies naturally produced by the body as a result of an infection, being specific for the infectious agent. In the first stage of infection, IgM levels increase and, therefore, it is considered an acute marker of infection.
As the disease develops, there is an increase in the amount of IgG in the blood, in addition to remaining circulating even after fighting the infection and, therefore, it is considered a memory marker. IgG levels also increase with vaccination, giving the person protection against the virus over time. Understand better how IgG and IgM work