If the patient has an increased antistreptolysin O in the blood, then this indicates the presence of streptococcal infection in the body. Such an analysis is not used for urgent diagnosis of diseases caused by these bacteria. After all, antibodies to streptococcus appear in the blood only on the eighth day of the disease. A month after the first manifestations of the pathology, their number reaches a maximum. However, streptococcal infections often produce complications such as glomerulonephritis and rheumatism. For the purpose of early identification of the consequences, this analysis is prescribed.
What is antistreptolysin?
Antistreptolysin O (ASL-O) is an antibody that neutralizes the group A streptococcus enzyme (streptolysin). When bacteria enter the body, ASL-O recognizes their antigens and interacts with them. Proteins - immunoglobulins are also involved in this process. As a result, bacterial toxins are neutralized and eliminated from the body.
The more bacteria there are in the body, the more antibodies are required to neutralize them. If ASL-O is increased in the analysis, then this indicates the presence of group A streptococci.
Indications for the study
A blood test for antistreptolysin O is prescribed if there is a suspicion of the presence of streptococcal infection. Indications for the study are the following pathologies:
- angina;
- scarlet fever;
- rheumatic diseases;
- otitis;
- osteomyelitis;
- glomerulonephritis;
- myocarditis;
- PANDAS Syndrome (tics and mental disorders in children after sore throat or scarlet fever).
It should be remembered that antibodies come back to normal only 6-12 months after the infection. Therefore, even after recovery in a person, antistreptolysin O can be increased. However, if such an analysis is performed with rheumatism, myocarditis or glomerulonephritis, then its results help to identify the etiology of the disease. If the level of antibodies to streptolysin is increased in the blood, then most likely, rheumatic or renal pathology is a complication of streptococcal infection.
How is the analysis carried out?
For analysis, blood is taken from a vein. Then the antibody titer is determined using a special test by latex agglutination method. In this way, you can quickly identify the concentration of antistreptolysin O.
A more complex diagnostic method is a blood test using a photometer and spectrophotometer. This allows for accurate quantitative measurement of antibody levels.
Usually, when examining a blood test for ASL-O, other immunological parameters are also determined:
- total protein;
- uric acid;
- C-reactive protein;
- circulating immune complexes.
Often, the doctor recommends taking an analysis twice. This is necessary in order to assess the dynamics of the disease and the effectiveness of the prescribed treatment.
Before passing the analysis, the following rules must be observed:
- The last meal should be no later than 8-12 hours before the study.
- On the eve of the analysis exclude physical activity.
- The day before the test exclude the use of alcohol.
- Within 1 hour before the study, you must refrain from smoking.
- It is undesirable to take medication before analysis. If the patient constantly uses any medications, then this should be reported to the doctor.
It should be remembered that sometimes antistreptolysin O is elevated for random reasons. The analysis can give false indicators if the patient took drugs, alcohol or smoked. Therefore, you must strictly adhere to the above rules. This is necessary for the reliability of the research results.
Norms of analysis
Normally, antistreptolysin O should not be contained in the blood. If antibodies to streptolysin are not detected, then this means that the patient has not experienced a streptococcal infection in the last 6 months.
However, if antibodies are detected in very small quantities, then this does not mean pathology. The maximum permissible values of ASL O are given in the table below.
| Patient age | up to 7 years | 7-14 years old | 14-18 years old | over 18 years old |
| The maximum indicator of ASL O (in units / ml) | 100 | 250 | 200 | 200 |
Reasons for increased antibodies
If antistreptolysin O is slightly increased, this indicates that a person has recently contracted streptococcus A. If the antibody titer significantly exceeds the norm, this indicates a long-standing presence of infection in the body.
If, after the start of treatment, the ASL-O indicator gradually decreases, then this indicates that the therapy is selected correctly.
An increased titer of antibodies to streptolysin can occur with the following pathologies:
- sore throat;
- myocarditis;
- hepatic pathologies;
- rheumatism;
- scarlet fever;
- erysipelas.
In some cases, an increase in ASL-O can be observed in healthy people. Therefore, you need to pay attention to other indicators of the analysis, such as the level of total protein and the presence of paraproteins.
What to do with an increased titer of antibodies?
What to do if antistreptolysin O is elevated in the blood? Treatment is prescribed only after additional research. The following tests must be done:
- biochemical blood test;
- test for creatine phosphokinase and lactate dehydrogenase.
It is also recommended to do an EEG and ultrasound of the heart. This will help detect myocarditis.
If the diagnosis is confirmed, then penicillin antibiotic therapy is prescribed:
Additionally prescribed corticosteroids and anti-inflammatory drugs.
If the patient has myocarditis, then the following drugs are indicated:
In case of kidney damage (glomerulonephritis), the patient is placed in a hospital. The patient is prescribed a salt-restricted diet. It is necessary to daily control the amount of urine and blood pressure released.
The main treatment for streptococcal infection and its complications is antibiotic therapy. However, it should be remembered that antibacterial drugs adversely affect the intestinal microflora. Therefore, it is necessary to take probiotics and try to use fermented milk products more often. The use of immunomodulators is also shown. Only an integrated approach to therapy will help to cope with streptococcal infection.