SED rate measures the amount of inflammatory activity in the human body, according to Mayo Clinic. It is a simple blood test that can help diagnose inflammatory conditions.
To determine a SED rate from a patient's blood, a blood sample can be placed into a tall test tube, according to Mayo Clinic. Gradually, the red blood cells in the blood sample settle into the bottom of the tube. When inflammation is present, red blood cells clump together and fall to the bottom of the test tube more quickly. During a SED rate test, the amount of red blood cells that settle at the bottom of the test tube is measured over 60 minutes. The higher the concentration of red blood cells, the more inflammation there is present in the patient's body.