Sedimentation Rate
Test Overview
The sedimentation rate (sed rate) blood test measures how quickly red blood cells (erythrocytes) settle in a test tube in one hour.
When inflammation is present in the body, certain proteins cause red blood cells to stick together and fall more quickly than normal to the bottom of the tube. The more red cells that fall to the bottom of a special test tube in one hour, the higher the sed rate. These proteins are produced by the liver and the immune system under many abnormal conditions, such as an infection, an autoimmune disease, or cancer. There are many possible causes of an elevated sedimentation rate. For this reason, a sed rate is done with other tests to confirm a diagnosis. Once a diagnosis has been made, a sed rate can be done to help monitor the course of the disease or the effectiveness of treatment.
Why It Is Done
A sedimentation rate (sed rate) test is done to:
Determine whether a condition causing inflammation is present.
Monitor the response to treatment of some conditions, such as an infection or some autoimmune diseases.
How To Prepare
No special preparation is needed before having this test.
How It Is Done
The health professional drawing blood will:
Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
Clean the needle site with alcohol.
Put the needle into the vein. More than one needle stick may be needed.
Attach a tube to the needle to fill it with blood.
Remove the band from your arm when enough blood is collected.
Apply a gauze pad or cotton ball over the needle site as the needle is removed.
Apply pressure to the site and then a bandage.
How It Feels
You may feel nothing at all from the needle puncture, or you may feel a brief sting or pinch as the needle goes through the skin. Some people feel a stinging pain while the needle is in the vein. However, many people do not feel any pain (or have only minor discomfort) once the needle is positioned in the vein. The amount of pain you feel depends on the skill of the person drawing the blood, the condition of your veins, and your sensitivity to pain.
Risks
Blood test
There is very little risk of complications from having blood drawn from a vein.
You may develop a small bruise at the puncture site. You can reduce the risk of bruising by keeping pressure on the site for several minutes after the needle is withdrawn.
Rarely, the vein may become inflamed after the blood sample is taken. This condition is called phlebitis and is usually treated with a warm compress applied several times daily.
Continued bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medications can also make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medication, tell your health professional before your blood is drawn.
Results
The sedimentation rate (sed rate) blood test measures how quickly red blood cells (erythrocytes) settle in a test tube.
Normal
Normal values may vary from lab to lab.
Sedimentation rate Males younger than 50:
0