Blood Test: Erythrocyte Sedimentation Rate (ESR)




Blood Test: Erythrocyte Sedimentation Rate (ESR)
What It Is



An erythrocyte sedimentation rate test, also called an ESR or sed
rate test, measures the speed at which red blood cells fall to the
bottom of an upright glass test tube. This measurement is important
because when abnormal proteins are present in the blood, typically due
to inflammation or infection, they cause red blood cells to clump
together and sink more quickly.

Why It's Done



The ESR is useful in detecting inflammation in the body that may be
caused by infection, some cancers, and certain autoimmune diseases such
as rheumatoid arthritis, lupus, and Kawasaki disease. The ESR alone
can't be used to diagnose any one specific disease, however.

Preparation



No special preparations are needed for this test. Having your child
wear a short-sleeve shirt on the day of the test can make things easier
for your child and the technician who will be drawing the blood.Continue


The Procedure



A health professional will usually draw the blood from a vein. For an
infant, the blood may be obtained by puncturing the heel with a small
needle (lancet). If the blood is being drawn from a vein, the skin
surface is cleaned with antiseptic, and an elastic band (tourniquet) is
placed around the upper arm to apply pressure and cause the veins to
swell with blood. A needle is inserted into a vein (usually in the arm
inside of the elbow or on the back of the hand) and blood is withdrawn
and collected in a vial or syringe.

After the procedure, the elastic band is removed. Once the blood has
been collected, the needle is removed and the area is covered with
cotton or a bandage to stop the bleeding. Collecting blood for this test
will only take a few minutes.



What to Expect



Either method (heel or vein withdrawal) of collecting a sample of
blood is only temporarily uncomfortable and can feel like a quick
pinprick. Afterward, there may be some mild bruising, which should go
away in a few days.

Getting the Results



ESR test results are usually available within a few hours or the next
day. If results seem to suggest inflammation, the doctor may order
further tests to determine the specific cause of the problem.

Risks



The ESR test is considered a safe procedure. However, as with many
medical tests, some problems can occur with having blood drawn, such as:

• fainting or feeling lightheaded
  
• hematoma (blood accumulating under the skin causing a lump or bruise)
  
• pain associated with multiple punctures to locate a vein
  

Helping Your Child



Having a blood test is relatively painless. Still, many kids are
afraid of needles. Explaining the test in terms your child can
understand might help ease some of the fear.

Allow your child to ask the technician any questions he or she might
have. Tell your child to try to relax and stay still during the
procedure, as tensing muscles and moving can make it harder and more
painful to draw blood. It also may help if your child looks away when
the needle is being inserted into the skin.

If You Have Questions



If you have questions about the ESR test, speak with your doctor.