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What is an Absolute Eosinophil Count (AEC) test? 

An AEC test is used to determine the number of eosinophils in the bloodstream. Eosinophils are a type of white blood cells (WBCs) that fight infections and worm infestations in the human body. They also help to regulate the responses of other WBCs by causing dilation of blood vessels and signalling the WBCs to reach the site of infection. Furthermore, eosinophils engulf pathogens and are known to show antiviral activity.

They also play an important role in regulating allergic responses in the body such as in asthma.

Ideally, the number of eosinophils in the bloodstream is very low. They have a short lifespan in the blood and mostly stay confined to tissues to perform their functions. However, an increased eosinophil count may indicate an active infection or allergy.

  1. Why is an AEC test performed?
  2. How do you prepare for an AEC test?
  3. How is an AEC test performed?
  4. What do AEC test results indicate?

Though eosinophil count is done along with a complete blood count (CBC), an AEC test result is more specific compared to the percentage value given in CBC. AEC is generally recommended in case of the following conditions:

Symptoms of allergies

  • Initial stage symptoms of Cushing syndrome 
  • Parasitic infections
  • Abnormal results from a full blood differential count
  • Acute hypereosinophilic syndrome (increased eosinophils without evidence)

The test is sometimes also performed if an individual has returned from a long trip from tropical areas, as they might be on the risk of picking up infections.

No special preparations are needed for this test. It is important that you inform your doctor about all the medicines or herbal supplements you may be taking since certain substances such as amphetamines, interferons, antibiotics, tranquilisers and laxatives containing psyllium can alter AEC results. 

If needed, the doctor may change the course of these medicines; however, one must not change the course without the consent of the doctor. It is also essential to tell the doctor if you have had any medical conditions in the past.

AEC is essentially a blood test, for which a small amount of blood will be taken from a vein in your arm at any time during the day. The site of the collection will first be cleaned using an antiseptic fluid, and a tourniquet will be tied around your arm. Blood will then be drawn using a sterile needle. The sample would be deposited in a sterile tube and sent to a lab for analysis.

If blood needs to be collected from an infant, a tiny prick will be made on their heel, and a few drops of blood will be deposited either on a glass slide, test strip or glass tube.

Once the blood is withdrawn, the technician will cover the site of puncture with a cotton gauze or bandage to stop bleeding and prevent infection. Needle insertion may cause slight pain or discomfort, which will disappear soon. 

Once the sample reaches the laboratory, it is observed under the microscope to count the number of eosinophils per 100 cells. Results are generally presented according to the blood volume.

Normal results: Normal values of AEC range from 450 to 550 cells/microlitres (µL), which indicates the absence of any underlying conditions. 

Abnormal results: AEC values less than the normal values are considered abnormal; this could be because of alcohol inebriation or certain steroids produced in excess in the body.

Higher than normal values of AEC are also considered abnormal and associated with various conditions. A higher value of eosinophils in the blood is known as eosinophilia. The following table gives a correlation between the values and the associated disorders.

Mild eosinophilia

550-1500 cells/µL

Asthma, allergic rhinitis, eosinophilic esophagitis, atopic dermatitis or drug allergy

Moderate eosinophilia

1500-5000 cells/µL

Allergic bronchopulmonary aspergillosis

Chronic sinusitis

Chronic eosinophilic pneumonia or certain drug allergies

Severe eosinophilia

More than 5000 cells/µL

In addition, mild-to-moderate eosinophilia can be caused by helminthic (worm) infections, such as

  • Ascariasis
  • Hookworm infection
  • Echinococcosis
  • Trichinellosis
  • Strongyloidiasis
  • Gnathostomiasis
  • Cysticercosis
  • Loiasis
  • Fluke infections

(Read more: Intestinal worms symptoms)

Many other autoimmune diseases and cancers can also be linked to increased levels of eosinophils in the blood. A few are listed below:

Your doctor may perform additional tests to identify the exact condition.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor. 

AEC (Absolute Eosinophil Count) Test की जांच का लैब टेस्ट करवाएं

Absolute Eosinophil Count - (AEC)

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References

  1. N. Adkinson Jr. et.al. Middleton's Allergy 2-Volume Set. 8th Edition, ISBN: 9780323085939
  2. Leslie Silberstein ,John Anastasi. Hematology. 6th Edition; Churchill Livingstone, ISBN: 9781455740413.
  3. Jenni Punt et.al. Kuby Immunology. 8th Edition; WH Freeman. [internet].
  4. Kovalszki A, Weller PF. Eosinophilia.. Prim Care. 2016 Dec;43(4):607-617. PMID: 27866580
  5. Christopher Sanford et.al. The Travel and Tropical Medicine manual . 5th Edition, ISBN: 9780323417426
  6. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services; Laboratory Procedure Manual
  7. Philip Lanzkowsky. Lanzkowsky's Manual Of Pediatric Hematology And Oncology. 6th edition, 2016. [internet].