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Hypereosinophilic Syndrome


Hypereosinophilic syndrome (HES) is a group of conditions that causes you to have too many eosinophils. An eosinophil is a type of white blood cell. Allergies, asthma, parasitic infections, and certain medicines may increase the number of eosinophils. Organs such as your skin, lungs, heart, or brain may be damaged if you have too many eosinophils. They may also harm your kidneys, intestines, liver, or spleen.


Informed consent

is a legal document that explains the tests, treatments, or procedures that you may need. Informed consent means you understand what will be done and can make decisions about what you want. You give your permission when you sign the consent form. You can have someone sign this form for you if you are not able to sign it. You have the right to understand your medical care in words you know. Before you sign the consent form, understand the risks and benefits of what will be done. Make sure all your questions are answered.


  • Immune modifying medicine decreases the number of eosinophils in your blood.
  • Steroids decrease pain and inflammation. They may also decrease the number of eosinophils in your blood and prevent further damage.


  • Blood tests will be done to measure the number eosinophils and other white blood cells.
  • Your bowel movement may be tested to see if you have parasites.
  • A chest x-ray is done to look at your heart and lungs.
  • An echocardiogram is a type of ultrasound. Sound waves are used to show the structure and function of your heart. It may be done to check for damage to your heart from HES.
  • A bone marrow biopsy is a procedure to remove a sample of bone marrow to be tested.


A bone marrow transplant is a procedure to replace your diseased bone marrow with healthy marrow. Bone marrow usually comes from a donor. The bone marrow is given to you in an IV while you are in the hospital.


Medicines or a bone marrow transplant may increase your risk for bleeding or infection. Ask your healthcare provider for more information about a bone marrow transplant.


You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your healthcare providers to decide what care you want to receive. You always have the right to refuse treatment.

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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Learn more about Hypereosinophilic Syndrome (Inpatient Care)

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Mayo Clinic Reference

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.