Erythrocyte sedimentation rate (ESR) blood tests are used to determine the amount of inflammation that is present in the body. They may be used to detect or monitor conditions such as tuberculosis, autoimmune disorders, inflammatory diseases, arthritis and tissue death. While these tests are used to screen for some diseases, they are not intended to diagnose a specific disorder.
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Clean the puncture site (usually inside the elbow) with antiseptic.
Apply a band around the upper arm to cause the veins at the puncture site to fill with blood.
Insert a needle attached to an air-tight syringe into the vein and collect the appropriate amount of blood.
Remove the band.
Withdraw the needle.
Cover the puncture site to stop any bleeding.
Take the blood sample to the lab immediately for processing.
Perform an ESR (erythrocyte sedimentation rate) blood test by placing anticoagulated blood in an upright Westergren tube.
Observe and report the rate at which the red blood cells fall to the bottom of the tube in mm per hour. The normal for men over 50 years old is a rate less than 20 mm per hour. The normal rate for men under 50 is below 15 mm per hour.
Expect women over 50 to be considered to have normal ESR readings at less than 30 mm per hour. For women under 50 years old, normal is below 20. Children vary from newborn readings at 0 to 2 mm per hour and neonatal to puberty at readings of between 3 to 13 mm per hour.
Look for any underlying factors that might increase the results of an erythrocyte sedimentation rate blood test. Conditions such as old age, pregnancy, anemia or elevated fibrinogen levels related to infection, inflammation or malignancy could cause the ESR result to read high.
Look at factors that can decrease the ESR reading such as extreme leukocytosis, polycythemia and protein abnormalities related to hypofibrinogenemia or hypogammaglobulinemia.
Expect to read the results of an erythrocyte sedimentation rate blood test in about an hour.
Tips and warnings
- Most ESR blood tests are read in the doctor's office. For an accurate reading, the tube must be positioned precisely upright. If the tube is leaning in any way, it will compromise the accuracy of the drop.
- A normal erythrocyte sedimentation rate is not to be used to rule out disease. If a cell is distorted, such as in the case of sickle cell disease, it may not stack correctly.