With frequent recurrences 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 cannot get measles, rubella, chicken pox and other infections again. What should be the normal concentration of immune group G proteins in the blood? And what is the reason for their increase or decrease? We will consider these issues in the article.
What is this
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, IgE and IgM proteins are first produced. They are trying to destroy the 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 tissues.
Immunoglobulins G is the most numerous group of protective proteins. They make up 70% of all antibodies. IgG proteins remain in the body for quite a long period. They are able to "remember" a foreign antigen and quickly destroy it when it enters the body again. Therefore, after some past infections, a person remains immune. This is the basis of most vaccines.
Functions in the body
Let's consider in more detail the role of immunoglobulins G in the body. These proteins perform the following functions:
- Stimulation of phagocytosis. IgG proteins speed up the uptake of antigens by other immune cells.
- Protection of the body from infections. IgG fight bacteria, fungi and viruses.
- Formation of strong immunity. Class G antibodies protect the body against re-entry of pathogens. These proteins quickly recognize the antigen they have encountered before.
- Binding of foreign proteins. IgG react with antigens. They render harmlessmicroorganisms and allergens. As a result, antigen-antibody complexes are formed, which are then removed from the body.
- Protection of the embryo during the intrauterine period. Class G antibodies cross the placenta and prevent infection of the fetus.
In infections, tumors, inflammations and allergic reactions, immunoglobulins G are elevated. Lymphocytes intensively produce these antibodies when foreign material enters the body. If the level of IgG is reduced, then this indicates a drop in immunity.
Indications
When can a doctor prescribe an immunoglobulin G test? There are the following indications for this study:
- frequent relapses of infectious and inflammatory diseases;
- autoimmune pathologies;
- immunodeficiency states;
- suspicion of malignant tumors;
- allergic reactions;
- hematological diseases;
- multiple myeloma;
- assessment of the results of immunoglobulin therapy.
To find out the content of class G antibodies, you need to take a special blood test. This test shows the state of the body's defense system and the activity of immune proteins.
Preparing for the study
In order for the immunoglobulin G values to be reliable, the following rules for preparing for analysis must be observed:
- 10-12 hours before sampling, stop eating. This analysis is taken on an empty stomach, before the study you can only drinkclean water.
- On the eve of the analysis, you should not eat fatty, spicy and fried foods, as well as alcoholic beverages.
- Heavy physical activity should be avoided the day before the test.
- You must refrain from smoking 2 hours before the examination.
It is important to remember that medications can affect the test result. 14 days before the analysis, you need to stop using antibiotics, analgesics, cytostatics, gold preparations, anticonvulsants and hormonal drugs. If this is not possible, then you need to tell the doctor about all the medications you take.
Sampling
The study takes blood from a vein. The biomaterial is sent to the laboratory. Usually, during the analysis, not only the level of antibodies of class G is determined, but also other groups of immunoglobulins.
Blood is examined by immunoelectrophoresis or immunofluorescence. Test results are usually available within 1-2 days.
Norma
What are the acceptable levels of immunoglobulin G? The levels of antibodies depend on the age of the patient. The table below shows the reference values of IgG.
| Age | IgG norm (in g/l) |
| up to 1 year | 2 - 14 |
| 1 - 3 years | 5 - 9 |
| 4 - 16 years old | 5 - 17 |
| 17 - 19 years old | 5 - 16 |
| over 20 | 7 - 16 |
IgG units may vary. In many laboratories the levelimmunoglobulin 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 from 35.5 to 147.5 mmol per 1 liter.
Reason for increase
Why can a person have elevated immunoglobulins G? Such a deviation from the norm is noted in the following pathologies:
- bacterial, viral, protozoal and fungal infections in acute and chronic form;
- sepsis;
- autoimmune pathologies;
- sarcoidosis (granulomatous process in tissues and organs);
- malignant tumors of hematopoietic organs;
- liver diseases (hepatitis, cirrhosis);
- neurosyphilis;
- worm infestations;
- food allergies;
- cystic fibrosis;
- monoclonal gammopathy (impaired production of immunoglobulins in lymphocytes);
- HIV infections;
- chronic purulent-inflammatory processes.
The results of the analysis of total immunoglobulins may not 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. Additional examinations are needed to make an accurate diagnosis.
Why IgG is low
Low concentration of class G antibodies is observed in the following pathologies and conditions:
- malignant tumors of the lymphatic system;
- radiation sickness;
- HIV-infections;
- severe burns;
- diseases of the gastrointestinal tract and kidneys, occurring with loss of proteins;
- after surgery to remove the spleen;
- atopic dermatitis;
- taking cytostatics and immunosuppressants.
It should be noted that with HIV infection, IgG levels 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 observed 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. Infants do not yet develop their own antibodies. Only maternal immunoglobulins provide protection against foreign agents. Therefore, reduced IgG at this age is a variant of the norm.
Features of analysis in pregnant women
During pregnancy, women take a blood test for antibodies to a specific virus. At the same time, the presence in the blood of immunoglobulins G and M, 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 malformations in the fetus. Therefore, such a study is considered mandatory during pregnancy.
The rules for preparing for this test are the same as for the analysis for generalimmunoglobulins. The interpretation of the results is as follows:
- G and M antibodies were not found in the analysis. This result of the study means that the woman is he althy, and her body has never encountered this infection before. Immunity against the virus is not formed.
- IgM missing, but IgG detected. What does this test result mean? These data indicate that the woman is currently he althy, but in the past she had a viral infection. She developed immunity against the pathogen.
- IgM is present in the blood, but there are no immunoglobulins G. The virus is active. This result is usually noted at the onset of an infectious disease.
- The analysis detected both types of antibodies - IgG and IgM. This indicates the presence of an infectious pathology. These results are most often seen in the midst of the disease.
What to do in case of deviations from the norm
How to normalize antibody levels? If a person has reduced 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 for the underlying pathology. After recovery or stable remission, the IgG level returns to normal.
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 class G antibodies. However, they are administered to combat a specific infectious agent.diseases. This therapy is not used to increase total IgG.
In case of deviations from the norm in the indicators of the analysis, doctors usually recommend additional studies. After the diagnosis is made, the patient is prescribed a course of treatment. Methods of therapy are selected individually, depending on the type of pathology.
