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Inflammation & Acute Phase
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Currently under review
Pending specialist review and validation.
The sedimentation rate, often called ESR, is a blood test that reflects the presence of inflammation in your body. It measures how quickly red blood cells settle to the bottom of a thin tube over a set period. When certain proteins associated with inflammation circulate in your blood, red blood cells tend to clump together and sink more quickly, which raises the measured rate.
This test is a general indicator rather than a diagnosis by itself. Clinicians usually interpret it alongside your symptoms, examination, and other laboratory tests such as C-reactive protein, since many different conditions can influence the result.
Your clinician may order an ESR if you have symptoms that could be caused by inflammation, such as persistent fever, headaches, fatigue, muscle aches, joint pain, or unexplained anemia. ESR can support the evaluation of conditions like temporal arteritis, polymyalgia rheumatica, rheumatoid arthritis, lupus, chronic infections, and some cancers.
ESR is also useful for monitoring how active an inflammatory condition is and how well treatment is working. Because ESR can be affected by factors unrelated to disease, it is most helpful when viewed over time and together with other clinical information.
A higher ESR suggests that some degree of inflammation may be present, but it does not identify the location or the cause. Your clinician will consider your result in the context of your history, physical examination, and other tests. A lower ESR can occur with conditions that change the number or shape of red blood cells, and sometimes has limited significance on its own.
If your result is unexpected, your clinician may repeat the test, review your medicines and recent illnesses, and order related tests such as C-reactive protein, a complete blood count, autoimmune antibody panels, or imaging. Pregnancy, older age, and anemia can raise the ESR, while dehydration, very high red blood cell counts, or certain inherited hemoglobin conditions can lower it.
When ESR is used to follow a known condition, the trend over time and how you feel are more important than any single value. Treatment decisions are based on the overall clinical picture.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Any active infection, autoimmune flare, or tissue injury can raise ESR by increasing inflammatory proteins that cause red blood cells to settle faster.
Low red blood cell counts, larger cell size, or abnormal shapes can make cells settle more quickly and raise ESR, while very high counts or some hemoglobin disorders can lower it.
ESR tends to be higher during pregnancy and can increase with older age, even without active disease, so your clinician interprets results with these factors in mind.
Corticosteroids and nonsteroidal anti-inflammatory drugs may reduce ESR by lowering inflammation, while oral contraceptives and some other medicines can increase it.
Delays before testing, incorrect tube position, temperature extremes, or improper mixing can alter sedimentation and lead to misleading results.
Kidney disease, obesity, and certain cancers can raise ESR independently of an acute infection, which is why results are interpreted with your overall health in mind.
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