What is an IgG Test?
Immunoglobulins do play a vital role in the immune system of a person. They are considered proteins that some specific immune cells, named plasma cells, produce by responding to viruses, bacteria besides other microorganisms, and exposures to various other substances that a human body recognizes as “non-self” dangerous antigens. This test does measure the presence of immunoglobulins, IgA, IgG, IgM in a person’s blood, and in some situations in CSF (cerebrospinal fluid) or saliva.
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An IgG test does measure the level of kinds of antibodies present in the blood. Your body makes various immunoglobulins or antibodies for combating various things. For instance, a person’s antibody for chickenpox is different from the antibody needed for mononucleosis. At times, a person’s body might make antibodies mistakenly against itself to treat healthy organs and some tissues, such as foreign invaders. It is known as an autoimmune disease.
What are the kinds of antibodies?
Some kinds of antibodies are as follows:
Immunoglobulin A or IgA – This is present in people’s digestive system and respiratory tract linings besides tears, breast milk, and saliva.
Immunoglobulin G or IgG – The IgG full form is Immunoglobulin G is considered the most ordinary antibody that remains present in various body fluids and blood. It protects the human body against viral and bacterial infections. IgG does take time to form after immunization or infection.
Immunoglobulin D or IgD – IgD is the least understood antibody, and it is present in only small amounts in a person’s blood.
Immunoglobulin E or IgE – IgE is commonly present in a person’s blood in small amounts. At times, there might be higher amounts too if the body does overreact to allergens or when it is fighting an infection caused by a parasite.
Immunoglobulin M or IgM – IgM is commonly found in lymph fluid and blood, and it is considered the first antibody that your body makes at the time of fighting a fresh infection.
What are IgG antibodies?
The IgG antibodies test against coronavirus checks the presence of some antibodies to the novel coronavirus named SARS CoV-2 present in the blood. When a person tests positive in an IgG antibody test, then it symbolizes that the person was exposed to this virus previously. However, it doesn’t indicate that the person has got this infection currently.
The importance of getting the Covid IgG antibody test
The physician might suggest getting an IgG antibody test done to check whether or not the person’s immune system or the defense of the body against illness has responded well to the infection of Covid-19. This is a blood test that is capable of detecting whether a person has got an antibody to SARS-CoV-2. This virus remains responsible for causing COVID-19. The antibody test for COVID-19 is helpful in identifying people who might have been contracted with the SARS-CoV-2 virus. This test also helps people who have recovered from the infection of COVID-19.
The significance of the Rubella Blood Test
A rubella blood test is helpful in detecting antibodies that a person’s immune system has made for killing the rubella virus. The presence of any antibody means a previous infection, a recent infection, or that the person has got vaccinated against a specific disease. The important thing is these antibodies remain present in a person’s bloodstream for many years.
Rubella is also known as 3-day measles or German measles, and commonly, it doesn’t give rise to long-term problems. However, if a woman during her pregnancy gets infected with this virus, then she can transmit this disease to the fetus or her baby. Some severe birth defects known as CRS (congenital rubella syndrome) can form, particularly at the time of the 1st trimester.
Some birth defects of congenital rubella syndrome comprise eye problems and cataracts, heart disease, and hearing impairment. Again, stillbirth and miscarriage too are some probable results for a pregnant woman. The vaccination for preventing rubella shields against these issues.
Commonly, a rubella test is done for women who want to become pregnant to determine whether or not she happens to be in danger of rubella. A few laboratory processes are utilized for detecting the presence of rubella antibodies present in the blood, and the most commonly utilized method is known as the ELISA or EIA or enzyme-linked immunosorbent assay.
Hopefully, this article successfully explained to you all about the IGG test.
FAQs on IgG Test
1. What is an IgG test and what does it measure?
An IgG test is a type of blood test known as a serological test that measures the amount of Immunoglobulin G (IgG) antibodies in your blood. IgG is the most abundant type of antibody in the bloodstream, making up about 75-80% of all immunoglobulins. The test helps determine if you have been exposed to a specific pathogen in the past, either through infection or vaccination, and have developed a long-term immune response.
2. What does a positive IgG test result indicate?
A positive IgG test result indicates that antibodies to a specific infectious agent (like a virus or bacterium) are present in your blood. This typically means you have either had a past infection or have been vaccinated against that agent. Unlike IgM antibodies which signal a recent infection, IgG antibodies signify a more mature, long-term immune response and provide lasting immunity.
3. Under what circumstances is an immunoglobulin test, like an IgG test, recommended?
A healthcare provider may recommend an immunoglobulin test, including an IgG test, under several circumstances, such as:
Investigating recurrent or severe infections, especially in the respiratory or digestive tracts.
Diagnosing and monitoring autoimmune conditions where the body produces antibodies against its own tissues, like in Rheumatoid Arthritis.
Evaluating a suspected primary or secondary immunodeficiency disorder.
Monitoring certain types of cancers, such as multiple myeloma, which affect antibody-producing cells.
4. What are the implications of having high or low IgG levels?
Abnormal IgG levels can indicate different health issues:
High IgG Levels (Hypergammaglobulinemia): Elevated levels may suggest a chronic infection (e.g., HIV, hepatitis), an autoimmune disease (e.g., lupus), or certain blood cancers like multiple myeloma. It shows the immune system is in a state of prolonged activation.
Low IgG Levels (Hypogammaglobulinemia): Depleted levels indicate a compromised immune system (immunodeficiency), making a person more vulnerable to infections. This can be due to genetic disorders (primary) or caused by other factors like medications or certain diseases (secondary).
5. How do IgG antibodies differ from IgM antibodies in an immune response?
IgG and IgM are two different classes of antibodies that appear at different stages of an immune response. The key difference between IgG and IgM lies in their timing and function:
IgM (Immunoglobulin M): This is the first antibody produced by the immune system when it encounters a new pathogen. Its presence in a blood test typically indicates a recent or ongoing infection.
IgG (Immunoglobulin G): This antibody is produced later in the immune response, usually taking 10-14 days to form. However, it persists for a long time, providing long-term immunity and memory. It is the primary antibody involved in the secondary immune response upon re-exposure to a pathogen.
6. Does a positive IgG test for a virus mean a person is currently contagious?
No, a positive IgG test does not necessarily mean a person is currently contagious. In fact, it usually suggests the opposite. IgG antibodies indicate a past infection or that the immune system has successfully fought off the virus and developed long-term protection. The presence of IgM antibodies is a much stronger indicator of an active, recent infection during which a person is more likely to be contagious.
7. Why is the IgG test crucial in understanding immunity from vaccines?
The IgG test is crucial because the primary goal of most vaccines is to stimulate the production of IgG antibodies and create immunological memory without causing the actual disease. After vaccination, a positive IgG test confirms that the body has successfully responded by creating these long-lasting protective antibodies. This indicates that if the person is exposed to the actual pathogen in the future, their immune system will be prepared to mount a rapid and effective defence.
8. Can IgG antibodies provide protection to a newborn baby?
Yes, IgG is the only class of antibody that can cross the placenta from the mother to the foetus during pregnancy. This process provides the newborn with passive immunity. The mother's IgG antibodies protect the infant from various infections for the first few months of life, a critical period when the baby's own immune system is still developing and not yet fully functional.
