Eosinophils are white blood cells that fight disease. A doctor can check your eosinophil level with a blood or tissue test. Eosinophilia is the condition that results when a person has a higher-than-normal amount of eosinophils. Eosinophilia usually indicates a parasitic infection, an allergic reaction, or cancer. Before you get too worried about your white blood cells fighting off illnesses, keep reading to learn more about eosinophils and the related condition. We'll look at symptoms, causes, diagnosis, and when to see a doctor.

Blood Testing for Eosinophils

A regular blood test is called a complete blood count and will be able to tell you whether you have high or low (or normal) levels of eosinophils. If your absolute eosinophil count is more than 500 per microliter of blood, you may have eosinophilia. Also, if your eosinophil count is more than 1500 per every microliter of blood, you could have a condition called hypereosinophilia.



Tissue Testing for Eosinophils

If you have an infection or inflammation on your body that concerns your physician, he or she may require a tissue test. By taking a sample from the site of inflammation, or sometimes the nose, the doctor can discover the number of eosinophils in your tissue. It is important to note that you may have normal levels of blood eosinophils, even if your tissue eosinophils are high.



What Roles Do Eosinophils Play?

In the immune system, eosinophils play an important role. They can decimate or "eat" foreign substances that don’t belong in your body. If you have an infection, the eosinophils will find the unknown substance and destroy it to ensure that your immune system remains healthy. They will also prompt inflammation at the site of infection, to prevent it from spreading further into your body.



General Causes

The causes of high or low levels of eosinophils vary from case to case and depend on existing medical conditions. Sometimes the body redirects a large number of eosinophils to a specific site. This is eosinophilia and is usually due to an infection.

Some health conditions such as autoimmune diseases, tumors, endocrine disorders, and skin conditions can prompt eosinophilia, as well. Specific diseases that can lead to eosinophilia include parasitic infections, asthma, Crohn's disease, and cancer. Allergic reactions and parasitic infections are the most common causes of high levels of eosinophils.



Rare Causes

Some conditions related to eosinophilia can be serious if not treated. Hypereosinophilic syndrome can cause organ damage. The cause is unknown, and doctors are still researching it.

Myeloproliferative neoplasms can damage bone marrow. Scientists believe neoplasms are probably the result of a mutation in an unknown gene.

When related to eosinophilia, this condition is called Myeloproliferative Hypereosinophilic Syndrome, or HES. To be diagnosed with HES, you must have persistent eosinophilia for six months or more, signs and symptoms of organ problems, and no other conditions that could cause eosinophilia.




Symptoms of high eosinophil levels vary from case to case. The most common symptom is inflammation. If you have an autoimmune disease such as rheumatoid arthritis, your joints are inflamed. Eosinophils will rush to the area in the hope of containing the problem.

If you have asthma, you may notice an increase in wheezing and difficulty breathing. Symptoms depend on what type of disease or infection you have.



When to See A Doctor

As long as you receive routine blood tests, your doctor can monitor your eosinophil levels. If you are experiencing a new symptom, especially inflammation, consult with your doctor. He or she will run tests to find the cause.

In the event that you have eosinophilia, your medical provider will monitor your levels to ensure an accurate diagnosis.




In most cases, treatment of eosinophilia is related to the condition that you have. For example, if you have an autoimmune disease, your doctor will treat it with steroid medications to decrease inflammation.

Proper treatment of your condition will regulate the levels of eosinophils in your body; since ridding the body of infection means the blood cells will no longer have an area to protect.



Support for Eosinophilia

There are support groups for people with rarer forms of eosinophilia. These groups enable patients to reach out to others with the disease and, as a result, gain insight into research and treatment options for conditions like hypereosinophilic syndrome. One of these groups is the American Partnership for Eosinophilic Disorders. 




Furthermore, if you have a condition that can cause eosinophilia, you can get involved in research. A program at The Centers for Mendelian Genomics is attempting to find the cause of rare genetic disorders like HES. You can apply to their research study or clinical trials for hypereosinophilia.



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This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.