What is EOS?

By | 28 April 2021

The immune system; produces white blood cells to fight bacteria, viruses, and other disease-causing agents that enter the body. These cells have many different types, each with different functions and characteristics. Depending on the type of white blood cells produced in the bone marrow, they have a lifespan that can range from a few hours to a few days. Instead of cells whose lifespan is exhausted, new cells are constantly produced by the immune system. Eosinophils, one of the white blood cells, are cells that have important functions in the immune system and are thought to be closely related to allergic diseases. Eosinophils are one of them, called complete blood count or hemogram, that are frequently investigated in blood tests to investigate many diseases. Abnormal eosinophil levels usually indicate the presence of an infection. Therefore, if the EOS level is found to be outside the normal value ranges in the blood count, the physician should be consulted.

What is EOS?

Eosinophils are a type of white blood cell (WBC) and their role in the body is not yet fully established. However, EOS levels are observed to increase significantly in allergic diseases and some infectious diseases. Eosinophils, which help fight infectious diseases, lead to increased inflammation. However, eosinophils are also effective in defending the body against some types of parasites. A significant increase in eosinophil levels can also damage the body’s own tissues, leading to the development of autoimmune conditions. Corticosteroids can be used to suppress eosinophils in chronic allergic and autoimmune diseases to prevent this.

When is the EOS test done?

Tests for white blood cells are performed under the name of complete blood count and the percentages of each blood cell in the blood are determined separately. The EOS test is also included in this test and allows the determination of the eosinophil count, its percentage in the blood. Abnormal EOS levels can be easily detected as a result of complete blood count. However, other white blood cells examined with the hemogram test are neutrophils, basophils, monocytes, and lymphocytes. The situations in which the EOS test is performed are a matter of curiosity by many patients. The level of eosinophils along with all blood cells can be an early indicator of many disorders in the body. Infectious diseases, autoimmune diseases, side effects of some drugs used, and many acute or chronic diseases manifest themselves with various disorders in blood count. Including the rising of the EOS level. Therefore, the investigation of the EOS test in blood count can be considered as a pre-test to determine the presence of any disorder regarding the general functioning of the body, to investigate the status of the immune system, and to investigate infections. Detecting EOS levels to be high requires further diagnostic tests for the cause.

What should be the EOS value?

Each laboratory determines reference ranges suitable for its own tests. Therefore, the reference range for EOS varies according to the laboratory where the test is performed. However, values ​​below 500 cells / MCL are considered normal for eosinophils according to the generally determined reference ranges. The range of 500-1000 cells / MCL indicates medium level, 500-1500 cells / MCL, 1500-5000 cells / MCL medium-high, values ​​above 5000 cells / MCL indicate high eosinophil level.

How is the EOS test done?

The EOS test is performed as a simple blood test that does not require any special preparation process beforehand. A blood count (hemogram) test, including the EOS test, can be performed with a single tube of blood. Although it varies depending on laboratory conditions and intensity, results can usually be obtained on the same day or the next day after the test. Patients for whom a blood count test has been requested should notify their physician in advance if they are using blood thinners such as Coumadin or Warfarin. Antibiotics, antimicrobial agents, some laxative drugs (laxatives), tranquilizers, and infectious drugs containing interferon can cause elevated EOS levels. Such special cases should be reported to the physician before the test. When starting the blood test, the area where the blood will be taken is first cleaned with the help of an antiseptic solution. Then the arm is clamped with the help of rubber and a needle is inserted into the vascular access. After a small amount of blood is taken into the vacuum tube, the needle is removed and the area is covered with a bandage. To prevent swelling and bleeding, it is beneficial to apply pressure to the area where blood is taken for 10 minutes. The blood sample taken is sent to the relevant laboratory for examination. The results obtained are evaluated by the physician.

What causes EOS height?

A high EOS value is an indicator that the amount of eosinophils in the blood has increased for any reason. This condition is also called eosinophilia. The increase in the amount of EOS can be caused by a variety of situations. Among the most common reasons for EOS height are:

  • Allergic diseases,
  • Infectious diseases,
  • Eczema,
  • Asthma,
  • Crohn’s disease
  • Some types of cancer
  • Celiac disease

There are some other types of autoimmune diseases.

The amount of EOS may increase due to the side effects of some drugs used. Therefore, while evaluating the results, the drugs used by the patient should be learned in detail. EOS value above normal can trigger various health problems. Increasing allergic reactions, damaging the body’s own tissues, and losing the strength of the immune system are some of the negativities caused by this situation. In some cases, especially mild elevations are considered normal or follow-up at regular intervals is recommended. The reason for this situation should be investigated by making further examinations required in line with the physician’s recommendations at a significant level of EOS.

Why is low EOS?

Low eosinophils do not make any medical sense. On the contrary, a low EOS value in the blood is desirable for healthy individuals. In some cases, low eosinophilia may be evaluated as a negative situation by the physician. This condition is called eosinopenia. Some of the conditions that may cause a decrease in eosinophil levels to include:

  • Excessive alcohol use
  • Problems with blood sugar regulation, hypoglycemia
  • Intense stress
  • Long-term use of birth control pills
  • Use of other hormone-containing drugs
  • Cushing’s syndrome and some other diseases that affect hormonal activity
  • Kidney and liver diseases and some other chronic diseases

In some cases, depending on the drugs used or general health status, slight increases and decreases in blood parameters can be evaluated as normal. On the contrary, in some patients, even a slight increase in EOS level may need to be taken seriously. For this reason, it is beneficial for every patient who has a blood count test to show the test results to his physician and act according to his physician’s evaluations.

How to correct high EOS values?

In patients with high EOS levels, underlying health problems should be investigated first to reach the normal ranges. Investigations should be made for the above-mentioned diseases that can cause eosinophil elevation. Taking the patient’s detailed history and learning the current diseases can explain some EOS heights. However, the drugs used can definitely be evaluated. In the case of eosinophilia caused by allergic diseases, antihistamine or corticosteroid treatments may help balance blood count parameters. In EOS heights that are thought to be caused by infection, the type of infection and the region where it develops should be determined. Following the determination of the agent causing the infection, EOS levels can be reduced to normal ranges with the use of antibiotic, antiviral, antifungal, or antiparasitic drugs. Eos elevation can also be caused by more serious diseases in some cases. Examples include certain types of cancer, including Hodgkin’s disease, inflammatory bowel disease, and some hormonal disorders. In such cases, after the underlying health problem is diagnosed, additional treatment should be applied accordingly.

If you see a high or low EOS level in your blood results, you can get information about the reasons for this situation by consulting your physician. If your physician deems it necessary, you can apply for more advanced diagnostic tests, allowing you to detect possible diseases at an early stage.


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