|Back to article|
Eosinophil count - absolute
An absolute eosinophil count is a blood test that measures the number of white blood cells called eosinophils. Eosinophils become active when you have certain allergic diseases, infections, and other medical conditions.
Eosinophils; Absolute eosinophil count
How the test is performed
Most of the time blood is drawn from a vein on the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around your upper arm to make the vein swell with blood.
Next, the heath care provider gently inserts a needle into the vein. The blood collects into an airtight tube attached to the needle. The elastic band is removed from your arm. The needle is then removed and the site is covered to stop bleeding.
In infants or young children, a sharp tool called a lancet may be used to prick the skin. The blood collects in a small glass tube, or onto a slide or test strip. A bandage is put on the spot to stop bleeding.
In the lab, the blood is placed on a microscope slide. A stain is added to the sample. This causes eosinophils to show up as orange-red granules. The technician then counts how many eosinophils are present per 100 cells. The percentage of eosinophils is multiplied by the white blood cell count to give the absolute eosinophil count.
How to prepare for the test
Most of the time adults do not need to take special steps before this test. Tell your doctor the medicines you are taking, including ones you buy without a prescription. Some drugs may change the test results.
Medicines that may cause you to have an increase in eosinophils include:
How the test will feelYou may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.
Why the test is performed
You will have this test to see if you have abnormal results from a blood differential test. This test may also be done if the doctor thinks you may have a specific disease.
This test may help diagnose:
Less than 350 cells per microliter (cells/mcL).
Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The example above shows the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
What abnormal results mean
A high number of eosinophils (eosinophilia) is often linked to allergic diseases and infections from parasites such as worms. A high eosinophil count may be due to:
A lower-than-normal eosinophil count may be due to:
What the risks are
There is very little risk involved with having your blood taken. Veins and arteries vary in size so it may be harder to take a blood sample in some people.
Other slight risks from having blood drawn are slight but may include:
The eosinophil count is used to help confirm a diagnosis. The test cannot tell if the higher number of cells is caused by allergy or parasite infection.
Roberts DJ. Hermatologic Aspects of Parasitic Diseases. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap 160.
Hutchinson RE, Schexineider KI. Leukocyteic Disorders. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 33.
Reviewed by:Todd Gersten, MD, Hematology/Oncology, Palm Beach Cancer Institute, West Palm Beach, FL. Review provided by VeriMed Healthcare Network.Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorousstandards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information andservices. Learn more about A.D.A.M.'s editorialpolicy, editorialprocess, and privacypolicy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch.)
The information provided herein should not be used during any medical emergency or for the diagnosis or treatmentof any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions.Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 2014 A.D.A.M., Inc. Any duplication ordistribution of the information contained herein is strictly prohibited.