Eosinophils (high or low): what does the test mean?

The human body is composed of several cells that, together, promote the proper functioning of the organism.

When performing blood cell exams, for example, different indications are presented and it is necessary to understand each item to evaluate the results.

One of the elements are Eosinophils, which help the immune system and are present in the plasma.


What are Eosinophils and what are they for?

Eosinophils are a type of white blood cell, that is, blood defense cells. They act on the body’s response, destroying foreign substances and controlling inflammation in the body. Thus, they are present in allergy conditions and in the fight against some parasites and infections.

Although they are also found in the bloodstream, most eosinophils are present in the body’s tissues.

They are generally fewer in the body than other white cells such as lymphocytes, which act against infections and tumors, for example.

The normal number of eosinophils in the blood can vary between 100 / µL and 500 / µL, that is, between 100 and 500 eosinophils for every milliliter of blood. If there is a big increase or decrease in these numbers, there may be complications.

Tall eosinophils: is it dangerous?

When the eosinophil count in the blood is high – greater than 500 / µL – this phenomenon is called Eosinophilia .
The problem can have three levels of severity, which vary according to the amount of cells found in the blood:

  • Light: 500 to 1,500 eosinophils / μL
  • Moderate: 1,500 to 5,000 eosinophils / μL
  • Severe: > 5,000 eosinophils / μL

In general, when the organism presents small variations in the levels of eosinophils, the patient does not suffer from side effects, and this increase may be due to normal conditions in some cases.

When to worry?

Despite being normal in some cases, eosinophilia can cause complications.

When the eosinophil count is equal to or greater than 1,500 / μL, this is classified as Hypereosinophilia – also called Hypereosinophilic Syndrome – and can cause tissue inflammation and damage to any organ in the body.

This, because in addition to the increase in blood, there is also the accumulation of these cells in some tissues.

Therefore, it is important to be alert if the eosinophil count is too high.

Low eosinophils: what does it mean?

When eosinophils are low in the blood, the condition is called Eosinopenia . It occurs when the numbers are below 40 eosinophils / µL.

Despite this, in general, the low count of this type of white blood cell in the body does not cause significant complications and symptoms.

This is because the body generally tends to balance the lack of eosinophils with the increase in other defense cells.

Treating the source of the problem tends to restore the adequate amount of these cells in the blood.

Zeroed eosinophils: is it serious?

Not necessarily. In some cases, the eosinophil percentage 0 may be somewhat normal.

There are 2 different ways to assess the number of eosinophils in the body.

The first, as already described in the previous topics, is done according to the number of eosinophils per milliliter of blood, taking into account the total number of these cells in the body.

The second way, on the other hand, displays the percentage of eosinophils in the blood compared to other defense cells, such as neutrophils, monocytes and basophils, for example.

In this case, the ideal percentage of eosinophils in the blood ranges from 1% to 4%.

However, if a complete blood count is performed – a test that assesses the count of different blood cells – and results in 0% eosinophils, it does not necessarily mean that the person has a disease.

The exams should not be evaluated in isolation, but in conjunction with the clinical history of each patient.

Thus, it may be that the percentage reset is a result of the increase in other defense cells, for example.

What causes the change in eosinophils?

The decrease or increase in the number of eosinophils in the body can have different causes, from diseases to the use of medications.

Possible sources of the problem include:


In general, a high number of eosinophils can be a sign of allergy such as asthma or atopic dermatitis . This is because they help the immune system in allergic responses.

Thus, when there are allergies in the body, there is an increase in these cells.


Infections caused by parasites can also be the cause of the elevation of eosinophils, since they act in the fight against foreign substances that invade the body.


Some cancers and autoimmune diseases can cause an increase in the rate of eosinophils, including:

  • Leukemia;
  • Hodgkin’s lymphoma;
  • Lupus;
  • Ulcerative colitis.

Corticosteroid medications

The causes of low levels of eosinophils in the body vary, and can be caused by infections in the blood or treatments with medications such as corticosteroids, for example.

These remedies are immunosuppressive, that is, they are used to suppress the body’s defense mechanisms. Thus, eosinophils consequently decrease.

Cushing’s syndrome

Cushing’s syndrome can also be one of the origins of the drop in the rate of cells. The disease is characterized by the excessive increase in cortisol, known as stress hormone , in the body.

Cortisol is a hormone released by the body in situations of tension and adrenaline. In the disease, this substance is usually produced in an excessive way.

The release of this hormone stimulates the decrease of eosinophils in the blood, which is one of the causes of eosinopenia.


Stressful situations release a large amount of cortisol. As with Cushing’s disease, this can affect eosinophil counts, lowering rates.


During pregnancy, there may be a decrease in the number of eosinophils in the body, however, not necessarily indicating signs of pathologies, which may be a physiological change.

How to identify the number of eosinophils?

The amount of eosinophils present in the blood can be identified using a blood count.

The blood count is a blood test that aims to assess the health of the patient as a whole.

It is used to measure the levels of the 3 basic blood plasma cells: red blood cells (red blood cells), white blood cells (leukocytes) and platelets, and to identify possible disorders and pathologies.

Like other blood tests, the blood count is effective in hospitals or laboratories, and the sample is taken through a collection of material.

In the result, several items are presented and, among them, the amount of eosinophils.

What are the symptoms of eosinophil changes?

When the numbers of eosinophils in the body are altered, some symptoms may appear.

They vary according to the severity of the condition, and there may not even be any manifestation in milder cases.

However, when there are critical situations, they can occur. Some of the symptoms are:


When eosinophils are high in the body, some symptoms can manifest. In general, they only occur in more severe cases.

Symptoms of eosinophil discharge may vary according to the organ affected by the problem.

For example, if the lungs are affected, there may be shortness of breath. If the affected organ is the stomach, it is possible that there will be pain in the area.

In general, the diseases caused by this type of disease are characterized by the nomenclature “eosinophilic” after the name of the problem.

Some examples are:

  • Eosinophilic pneumonia – eosinophils accumulated in the lung;
  • Eosinophilic gastritis – infiltration of eosinophils in the stomach;
  • Eosinophilic enteritis – infiltration of eosinophils in the small intestine.

In addition, some general symptoms may occur. Between them:

  • Weight loss;
  • Fever;
  • Cough;
  • Chest pain;
  • Fatigue;
  • Ache;
  • Rash;
  • Weakness;
  • Swelling.


When there is a low level of eosinophils in the body, in general, the body does not show expressive symptoms.

Thus, the lack of these cells is usually discovered at random, when performing tests for other purposes, not necessarily by the patient’s signals.

Treatment: how to increase the number of eosinophils?

In different situations, there may be a drop in the levels of eosinophils in the blood. Generally, to normalize this situation, it is enough to combat the origin of the variation.

Thus, if eosinophils are in small amounts in the body, it is not necessary to take steps to increase these cells.

In general, the identification and treatment of the cause of the problem naturally increases the levels of eosinophils in the blood, returning to its ideal amount.

Urine eosinophil research: what is it for?

The urine test is usually done to help identify health problems when evaluating the cells present in the substance.

The identification of eosinophils in urine can help in the diagnosis of diseases such as interstitial nephritis – kidney inflammation – and atheroembolic kidney disease – one of the causes of kidney failure.

This is because, in general, there is naturally a small amount of these cells in the urine, about 1%. When found in greater quantities, they are generally indicative of the presence of disease.

Understanding the components of our body is important to know what health care to take.

Eosinophils are defense cells that are present in the blood and assist the immune system in allergic responses.

When they are lacking or excess in the body, they can cause some disturbances.

If the change in the number of these cells is diagnosed, it is important to seek medical help, which will indicate the best treatment for each clinical condition.

Want to know more about health and the human body ? The Healthy Minute has other complete content for you! Read more and stay informed!