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Sedimentation Rate (Sed Rate)

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.
  • 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 can't 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. To learn more, see the topic C-Reactive Protein (CRP).


  1. Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

Other Works Consulted

  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

  • Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.

ByHealthwise Staff
Primary Medical ReviewerAnne C. Poinier, MD - Internal Medicine
Specialist Medical ReviewerKathleen Romito, MD - Family Medicine

Current as ofSeptember 9, 2014

1 | 2 | 3

WebMD Medical Reference from Healthwise

Last Updated: September 09, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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