Immunoglobulin G: indications, norms, causes of deviations and features

With frequent relapses of infectious diseases, doctors prescribe a blood test for immunoglobulin G (IgG). Why is this needed? What does such an analysis show? Immunoglobulins are proteins that play a leading role in the formation of stable immunity. Thanks to these substances, a person can not get sick with measles, rubella, chickenpox and other infections. What should be the normal concentration of group G immune proteins in the blood? And what is the reason for their increase or decrease? We will consider these issues in the article.

What it is

Immunoglobulins (Ig) are protein compounds that are formed when a foreign agent (antigen) enters the body. Otherwise, they are called antibodies. These substances are necessary for the formation of the immune response and the fight against the disease. In total, there are 5 classes of such proteins:

• A (IgA).
• G (IgG).
• M (IgM).
• E (IgE).
• D (IgD).

Each group of antibodies is responsible for a specific immune response. When an antigen enters the body, the IgE and IgM proteins are first produced. They are trying to destroy an alien agent. A few days later, class G immunoglobulins begin to form in the body. These antibodies are produced by special cells - lymphocytes. They continue to fight the antigen. IgG is found not only in the blood, but also in the tissues.

Immunoglobulins G is the largest group of protective proteins. They make up 70% of all antibodies. IgG proteins remain in the body for a rather long period. They are able to "remember" a foreign antigen and quickly destroy it when it is re-introduced into the body. Therefore, after some infections, a person has a strong immunity. The effect of most vaccines is based on this.

Body functions

Let us consider in more detail the role of immunoglobulins G in the body. These proteins perform the following functions:

1. Stimulation of phagocytosis. IgG proteins accelerate the absorption of antigens by other immune cells.
2. Protecting the body from infections. IgG fights bacteria, fungi and viruses.
3. The formation of persistent immunity. Class G antibodies protect the body against the re-entry of pathogens. These proteins quickly recognize the antigen that they have previously encountered.
4. The binding of foreign proteins. IgGs react with antigens. They neutralize microorganisms and allergens. As a result, antigen-antibody complexes are formed, which are then removed from the body.
5. Protection of the embryo in the prenatal period. Class G antibodies cross the placenta and prevent fetal infection.

With infections, tumors, inflammations and allergic reactions, immunoglobulins G are elevated. Lymphocytes intensely produce these antibodies when foreign material enters the body. If the level of IgG is reduced, then this indicates a decrease in immunity.

Indications

When can a doctor prescribe an immunoglobulin G test? The following indications for this study exist:

• frequent relapses of infectious and inflammatory diseases;
• autoimmune pathologies;
• immunodeficiency states;
• suspected malignant tumors;
• allergic reactions;
• hematologic diseases;
• myeloma
• evaluation of the results of therapy with immunoglobulin preparations.

To find out the content of class G antibodies, you must take a special blood test. This test shows the state of the body's defense system and the activity of immune proteins.

Study preparation

In order for immunoglobulin G indicators to be reliable, the following rules for preparing for analysis must be observed:

1. 10-12 hours before taking the sample, you need to stop eating. This test is taken on an empty stomach, before the test you can drink only clean water.
2. On the eve of the analysis, you can not eat fatty, spicy and fried foods, as well as alcohol.
3. The day before the test you need to avoid heavy physical exertion.
4. 2 hours before the study, you must refrain from smoking.

It is important to remember that medication may affect the test result. 14 days before the analysis, you need to stop using antibiotics, analgesics, cytostatics, gold preparations, anticonvulsants and hormones. If this is not possible, then you need to tell your doctor about all the medications you take.

Sampling

Blood is taken from a vein for examination. Biomaterial sent to the laboratory. Usually, during the analysis, not only the level of class G antibodies is determined, but also other groups of immunoglobulins.

Blood is examined by immunoelectrophoresis or immunofluorescence. Analysis results are usually ready in 1-2 days.

Norm

What are the acceptable rates of immunoglobulin G? Norms of antibody content depend on the age of the patient. The table below shows the reference values ​​of IgG.

The units of measure for IgG may be different. In many laboratories, the level of immunoglobulin G is calculated in micromoles per 1 liter of blood. In this case, you can easily recalculate the test results using the formula: 1 mmol = 6.67 g / l. The norm for an adult is indicators from 35.5 to 147.5 mmol per 1 liter.

Reasons for the increase

Why can a person have increased immunoglobulins G? Such a deviation from the norm is noted with the following pathologies:

• bacterial, viral, protozoal and fungal infections in acute and chronic form;
• sepsis
• autoimmune pathologies;
• sarcoidosis (granulomatous process in tissues and organs);
• hematopoietic malignancies;
• liver diseases (hepatitis, cirrhosis);
• neurosyphilis;
• helminthic infestations;
• food allergies;
• cystic fibrosis;
• monoclonal gammopathy (impaired production of immunoglobulins in lymphocytes);
• HIV infection
• chronic purulent-inflammatory processes.

The results of the analysis for general immunoglobulins cannot indicate a specific disease. A high level of class G antibodies only indicates the presence of an immune response to the invasion of a foreign agent. To make an accurate diagnosis, additional examinations are needed.

Why IgG is reduced

A low concentration of class G antibodies is observed in the following pathologies and conditions:

• malignant tumors of the lymphatic system;
• radiation sickness;
• HIV infection
• severe burns;
• diseases of the gastrointestinal tract and kidneys, occurring with the loss of proteins;
• after surgery to remove the spleen;
• atopic dermatitis;
• taking cytostatics and immunosuppressants.

It should be noted that with HIV infection, IgG values ​​can deviate from the norm, both up and down. In some cases, immunoglobulin G is elevated, while in others it is sharply reduced.

Also, a low level of IgG is noted in congenital pathologies: Wiskott-Aldrich syndrome and Bruton's disease. These genetic abnormalities are characterized by an almost complete absence of antibody production.

Immunoglobulin G in a child under the age of 9 months is often below normal. Babies have not yet developed their own antibodies. Protection against foreign agents is provided only by maternal immunoglobulins. Therefore, reduced IgG at this age is a normal variant.

Features of the analysis in pregnant women

During pregnancy, women take a blood test for antibodies to a particular virus. In this case, the presence of immunoglobulins G and M in the blood produced against a certain type of pathogen is determined. Some viral infections (rubella, cytomegaly) are very dangerous for the expectant mother. These diseases can cause fetal malformations. Therefore, such a study is considered mandatory during pregnancy.

The rules for preparing for this test are the same as for the analysis for general immunoglobulins. The interpretation of the results is as follows:

1. Antibodies G and M were not found in the analysis. Such a study result means that the woman is healthy and her body has never encountered this infection before. Immunity against the virus is not formed.
2. There is no IgM, but immunoglobulin G is detected. What does this test result mean? These data indicate that the woman is currently healthy, but has had a viral infection in the past. She has formed immunity against the causative agent of the disease.
3. IgM is present in the blood, but there are no immunoglobulins G. The virus is active. This result is usually observed at the beginning of an infectious disease.
4. Both types of antibodies, IgG and IgM, were detected in the analysis. This indicates the presence of an infectious pathology. Such results are most often observed at the height of the disease.

What to do in case of deviations from the norm

How to normalize antibody performance? If a person has lowered or increased immunoglobulin G, then this is only one of the symptoms of the disease. Therefore, it is necessary to undergo a course of treatment of the main pathology. After recovery or persistent remission, the level of IgG normalizes.

It is important to remember that a low level of G antibodies leads to a weakening of the body's defenses. Therefore, such patients should avoid contact with infectious patients and hypothermia.

There are special sera that increase the formation of antibodies of class G. However, they are administered to combat a specific causative agent of an infectious disease. Such therapy is not used to increase the total amount of IgG.

If there are deviations from the norm in terms of analysis, doctors usually recommend additional studies. After diagnosis, the patient is prescribed a course of treatment. The methods of therapy are selected individually, depending on the type of pathology.