Results

The sedimentation rate (sed rate) blood test measures how quickly red blood cells (erythrocytes) settle in a test tube.

Normal

The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Results are usually available right away.

High values

High sedimentation rates may be caused by:

• Autoimmune diseases, such as systemic lupus erythematosus or rheumatoid arthritis.
• Cancer, such as lymphoma or multiple myeloma.
• Chronic kidney disease.
• Infection, such as pneumonia, pelvic inflammatory disease, or appendicitis.
• Inflammation of joints (such as polymyalgia rheumatica) and blood vessels (such as giant cell arteritis).
• Inflammation of the thyroid gland (Graves' disease).
• Kidney, bone, joint, skin, or heart valve infections.
• Pregnancy and preeclampsia (toxemia of pregnancy).
• Viral infections.

Low values

Low values may be caused by:

• High blood sugar levels.
• Polycythemia.
• Sickle cell disease.
• Severe liver disease.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Pregnancy.
• Anemia.
• Having your menstrual period.
• Age. Sed rates normally increase with age.
• Medicines. Many medicines can change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.

What To Think About

• Even though some problems, such as giant cell arteritis, almost always cause a high sedimentation rate (sed rate), the test cannot be used by itself to identify a specific disease. Results of a sed rate test are considered along with your symptoms, other test results, and medical information.
• Some diseases that cause inflammation do not increase the sed rate, so a normal sed rate does not always rule out a disease.
• Some doctors use the C-reactive protein (CRP) blood test instead of the sed rate test to help identify inflammatory conditions. For more information, see the topic C-Reactive Protein (CRP).