Eosinophil count

This test counts the number of eosinophils (a type of white blood cell) in blood. It is used to evaluate and manage allergic conditions, blood and infectious diseases (including disseminated eosinophilic collagen disease and asthma), as well as certain infections.

Laboratory tests may be done for many reasons. Tests are performed for routine health screenings or if a disease or toxicity is suspected. Lab tests may be used to determine if a medical condition is improving or worsening. Lab tests may also be used to measure the success or failure of a medication or treatment plan. Lab tests may be ordered for professional or legal reasons. You may need this test if you have:

• Allergic eczema
• Asthma
• Disseminated eosinophilic collagen disease
• HIV infection
• Infection by Anisakis larva
• Infection by larvae of Trichinella spiralis
• Infection by Schistosoma
• Infection by Strongyloides

Venous or capillary blood:

Before having blood collected, tell the person drawing your blood if you are allergic to latex. Tell the healthcare worker if you have a medical condition or are using a medication or supplement that causes excessive bleeding. Also tell the healthcare worker if you have felt nauseated, lightheaded, or have fainted while having blood drawn in the past.

Tell the person doing the test if you smoke.

A sample of venous or capillary blood may collected for this test.

Venous blood:

When a blood sample from a vein is needed, a vein in your arm is usually selected. A tourniquet (large rubber strap) may be secured above the vein. The skin over the vein will be cleaned, and a needle will be inserted. You will be asked to hold very still while your blood is collected. Blood will be collected into one or more tubes, and the tourniquet will be removed. When enough blood has been collected, the healthcare worker will take the needle out.

Capillary blood:

Common sites to collect a capillary blood sample are the fingertip and earlobe. Infants often have a capillary blood sample taken from the heel of the foot. Once the site is selected, the healthcare worker may heat the area with a warm compress to ensure adequate blood flow. The area will be cleaned with antiseptic. A small needle is used to make a cut in the skin surface, and the area may be squeezed gently to produce blood. The blood is collected in small collection device.

The amount of discomfort you feel will depend on many factors, including your sensitivity to pain. Communicate how you are feeling with the person doing the test. Inform the person doing the test if you feel that you cannot continue with the test.

Venous or capillary blood:

During a blood draw, you may feel mild discomfort at the location where the blood sample is being collected.

Venous blood:

After a blood sample is collected from your vein, a bandage, cotton ball, or gauze may be placed on the area where the needle was inserted. You may be asked to apply pressure to the area. Avoid strenuous exercise immediately after your blood draw. Contact your healthcare worker if you feel pain or see redness, swelling, or discharge from the puncture site.

Capillary blood:

After capillary blood collection is complete, cotton will be placed over the site and held firmly until the bleeding has stopped. A bandage or cotton may be secured over the site.

You have the right to help plan your care. To help with this plan, you must learn about your health condition and how it may be treated. You can then discuss treatment options with your caregivers. Work with them to decide what care may be used to treat you. You always have the right to refuse treatment.