Diseases > Erythrocyte Sedimentation Rate (ESR)
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Erythrocyte Sedimentation Rate (ESR)
The Erythrocyte Sedimentation Rate (ESR) is a very common test used in rheumatology. The ESR is used to help determine the “level of inflammation” in your body. What? Let’s step back a little bit so you understand.
The word inflammation comes from the latin word “inflamare” which means to set or put on fire. In the olden days when a part of the body was swollen, warm, painful, and red it was thought to “be on fire” … inflamare. Nowdays, we use the word inflammation to mean something that is painful, warm, swollen, and red. If one of your joints is swollen, warm, and painful (in truth it doesn’t always have to be red) it is called inflamed.
It’s important to remember that lots of things can cause inflammation. An infection causes inflammation. Uric acid crystals in gout cause inflammation. Autoimmune diseases like lupus or rheumatoid arthritis cause inflammation. The ESR test can sometimes tell us if there is inflammation but it can’t tell us why.
If something in the body is inflamed we can look to see if we can see evidence of this inflammation in the blood. For this we can use a test like the ESR. The ESR is increased during inflammation.
- The ESR test does not tell us why there is inflammation in the first place
- The ESR test can be increased in other conditions
The best use of the ESR is to follow inflammation levels. Let’s say you’ve got rheumatoid arthritis and your doctor measures you ESR and it is elevated. Then your doctor starts you on treatment and your ESR falls as the disease improves.
As the ESR test can go up and down for many reasons it’s important not to “treat” the test. You have to make sure the ESR test “matches up” with the symptoms. Here’s an example. A person comes in with a condition called polymyalgia rheumatica (PMR) with a high ESR. Initially the ESR test improves a great deal with prednisone therapy and they feel much better. However, at a later date as the dose of prednisone is reduced the person feels unwell and the ESR becomes elevated again. The initial thought is to increase the prednisone again as the PMR is “flaring”. However, after looking carefully it is discovered that this person has a urinary tract infection and the reason the ESR is increased is because of this infection causing “inflammation” in the bladder. So the person is put on an antibiotic and the prednisone is not increased and things improve. If your ESR goes up it is important to try and understand why. Sometimes this can be difficult.