The ESR (erythrocyte sedimentation rate), often called a "sed rate," is a simple blood test in which a sample of blood is placed in a tall, thin tube and the lab measures how fast the red blood cells (erythrocytes) settle toward the bottom over one hour, reported in millimeters per hour (mm/hr). When there is inflammation, certain proteins cause red blood cells to clump together, and these heavier clumps sink faster; the result is a general, indirect marker of inflammation in the body, not a test for any one disease.
A clinician may order an ESR to help detect or monitor conditions that involve inflammation, usually alongside other tests, when someone has symptoms such as unexplained fever, headaches, joint stiffness, neck or shoulder pain, unexplained weight loss, loss of appetite, or anemia. It can also help monitor a known condition or its response to treatment, and a C-reactive protein (CRP) test is commonly done with an ESR to give more information.
Reference ranges are GENERAL and vary by laboratory, by the method used (e.g., the Westergren method), and by a person's age and sex — your own lab report and its listed reference range are what matter for you, and MedlinePlus notes that "normal value ranges may vary slightly among different labs." As a general illustration from MedlinePlus using the Westergren method, typical adult values are roughly: men under 50, less than 15 mm/hr; men over 50, less than 20 mm/hr; women under 50, less than 20 mm/hr; women over 50, less than 30 mm/hr; example child values are newborn 0 to 2 mm/hr and newborn to puberty 3 to 13 mm/hr. These numbers are general information only and are not a personal diagnosis; factors such as pregnancy, menstruation, older age, obesity, regular alcohol use, exercise, and some medicines or supplements can also affect the result.
A higher (faster) ESR may suggest more inflammation somewhere in the body, but it does not identify the cause on its own. Per MedlinePlus, a raised ESR can be seen with a wide range of conditions, which may include certain infections, rheumatoid arthritis and other autoimmune conditions (such as lupus), polymyalgia rheumatica, giant cell arteritis and other forms of vasculitis, inflammatory bowel disease, kidney or thyroid disease, anemia, pregnancy, and some cancers such as lymphoma or multiple myeloma. This is a general, hedged, and incomplete list of possible associations, not a diagnosis; MedlinePlus states that "an ESR test alone cannot diagnose which condition is causing the inflammation."
A lower (slower) ESR is less commonly the focus of testing, but MedlinePlus notes it can sometimes be seen with certain blood or other conditions, which may include polycythemia, sickle cell disease, leukemia or a high white-cell count, low plasma protein or low fibrinogen levels, hyperviscosity, and congestive heart failure. These are general possible associations only — hedged and incomplete — and are not a diagnosis. An ESR result is one piece of information: a high or low value does not by itself confirm or rule out any condition, and your clinician interprets it together with your symptoms, history, physical exam, and other tests. This is general information, not medical advice.
Reference ranges vary by laboratory, age, sex, and method — the range on your own report is what applies to you. A single value out of range doesn’t confirm any condition; your clinician interprets it alongside your symptoms, history, and other results. This page is general information, not medical advice.
General reference, not medical advice, and not a substitute for your clinician. Lab reference ranges and interpretation depend on the laboratory and on your individual situation — discuss your results with a licensed healthcare professional.