Also known as: Sed rate, Sedimentation rate
Formal name: Erythrocyte sedimentation rate
How is it used?Formal name: Erythrocyte sedimentation rate
The ESR is an easy, inexpensive, nonspecific test that has been used for many years to help diagnose conditions associated with acute and chronic inflammation, including infections, cancers, and autoimmune diseases. ESR is said to be nonspecific because increases do not tell the doctor exactly where the inflammation is in your body or what is causing it, and also because it can be affected by other conditions besides inflammation. For this reason, ESR is typically used in conjunction with other tests.
ESR is helpful in diagnosing two specific inflammatory diseases, temporal arteritis and polymyalgia rheumatica. A high ESR is one of the main test results used to support the diagnosis. It is also used to monitor disease activity and response to therapy in both of these diseases.
When is it ordered?
A physician usually orders an ESR test (along with others) to evaluate a patient who has symptoms that suggest polymyalgia rheumatica or temporal arteritis, such as headaches, neck or shoulder pain, pelvic pain, anemia, unexplained weight loss, and joint stiffness. There are many other conditions that can result in a temporary or sustained elevation in the ESR.
Since ESR is a nonspecific marker of inflammation and is affected by other factors, the results must be used along with the doctor’s other clinical findings, the patient’s health history, and results from other appropriate laboratory tests. If the ESR and clinical findings match, the doctor may be able to confirm or rule out a suspected diagnosis. A single elevated ESR, without any symptoms of a specific disease, will usually not give the physician enough information to make a medical decision.
Before doing an extensive workup looking for disease, a doctor may want to repeat the ESR test after a period of several weeks or months. If a doctor already knows the patient has a disease like temporal arteritis (where changes in the ESR mirror those in the disease process), she may order the ESR at regular intervals to assist in monitoring the course of the disease. In the case of Hodgkin’s disease, for example, a sustained elevation in ESR may be a predictor of an early relapse following chemotherapy.
ESR and C-reactive protein (CRP) are both markers of inflammation. Generally, ESR does not change as rapidly as does CRP, either at the start of inflammation or as it goes away. CRP is not affected by as many other factors as is ESR, making it a better marker of inflammation. However, because ESR is an easily performed test, many doctors still use ESR as an initial test when they think a patient has inflammation.
If the ESR is elevated, it is typically a result of globulins or fibrinogens. Your doctor may then order a fibrinogen level (a clotting protein that is another marker of inflammation) and a serum protein electrophoresis to determine which of these (or both) is causing the elevated ESR.
Females tend to have higher ESR, and menstruation and pregnancy can cause temporary elevations.
In a pediatric setting, the ESR test is used for the diagnosis and monitoring of children with rheumatoid arthritis or Kawasaki’s Disease.
Drugs such as dextran, methyldopa (Aldomet), oral contraceptives, penicillamine procainamide, theophylline, and vitamin A can increase ESR, while aspirin, cortisone, and quinine may decrease it.
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