ESR / Erythrocyte Sedimentation Rate

Erythrocyte Sedimentation Rate (ESR) measures how quickly red blood cells settle in a tube over a set period. It is a nonspecific marker, so the result is usually considered alongside symptoms, examination and other tests rather than used on its own to identify a particular condition.

ESR measures how quickly red blood cells settle in a vertical tube over one hour. Inflammation can alter proteins in plasma and make red cells settle faster, which is why ESR is used as a nonspecific marker of inflammation.

Because many unrelated conditions can raise ESR, the test is usually more useful as part of a pattern or trend than as a stand-alone diagnostic result. Age, sex, anaemia and pregnancy can also influence the value. CRP is another inflammation marker and may change more quickly in response to acute inflammation, so the two tests are sometimes considered together.

ESR is often most useful when there is a defined clinical question rather than as a stand-alone screening test. In some situations it is requested alongside CRP because the two markers behave differently over time. ESR can remain elevated longer after an inflammatory episode, while CRP may change more quickly. If the result is unexpectedly high or does not match the person’s symptoms, the clinician may review the CBC, medicines, pregnancy status, chronic conditions and previous ESR values before deciding whether further investigation is needed.

ESR may be requested when a clinician is looking for evidence of inflammation or monitoring an inflammatory condition over time. It is nonspecific, so it is usually interpreted with symptoms and other tests rather than used as a stand-alone diagnosis.

ESR is a nonspecific marker: it reflects how quickly red blood cells settle in a tube over a set period. A higher ESR can occur with inflammation, infection, autoimmune disease and several other conditions, but the result does not indicate where the problem is or what caused it. Age, sex, anaemia, pregnancy and some chronic conditions can also influence the measurement.

Clinicians often interpret ESR together with symptoms and other investigations, sometimes including CRP or a repeat ESR. A change over time can be more useful than a single mildly abnormal result when the test is being used to monitor an established condition.

ESR is not a screening test for a specific disease and it is not sufficiently specific to diagnose infection, autoimmune disease or cancer. A normal ESR cannot exclude all inflammatory conditions. Because the value is affected by red-cell characteristics and demographic factors, the result should be interpreted with the laboratory method, age-related context and the clinical reason for testing.

ESR uses a blood sample collected into the tube required by the laboratory method. Fasting is usually unnecessary for ESR alone. The sample should be handled and tested according to laboratory timing requirements because delayed processing can affect sedimentation.