Sed rate, or erythrocyte sedimentation rate (ESR), is a blood test that can reveal inflammatory activity in your body. A sed rate test isn't a stand-alone diagnostic tool, but it can help your doctor diagnose or monitor the progress of an inflammatory disease.
When your blood is placed in a tall, thin tube, red blood cells (erythrocytes) gradually settle to the bottom. Inflammation can cause the cells to clump. Because these clumps are denser than individual cells, they settle to the bottom more quickly.
The sed rate test measures the distance red blood cells fall in a test tube in one hour. The farther the red blood cells have descended, the greater the inflammatory response of your immune system.
July 02, 2016
- Shmerling RH. Evaluation of the adult with polyarticular pain. http://www.uptodate.com/home. Accessed May 20, 2016.
- Goldman L, et al., eds. Laboratory testing in rheumatic diseases. In: Goldman-Cecil Medicine. 25th ed. Philadelphia, Pa.: Saunders Elsevier; 2016. http://www.clinickey.com. Accessed May 20, 2016.
- Brigden ML. Clinical utility of the erythrocyte sedimentation rate. American Family Physician. 1999;60:1443.
Sed rate (erythrocyte sedimentation rate)