An ESR blood test, also known as a sed rate or erythrocyte sedimentation rate, is a simple blood test that indirectly measures the level of certain proteins in your blood. This measurement helps healthcare providers assess the level of inflammation in your body.
How the Test Works
The test measures how quickly red blood cells (RBCs) settle at the bottom of a special test tube. In the presence of inflammation, proteins such as fibrinogen and immunoglobulins cause the red blood cells to clump together and settle faster. A faster sedimentation rate generally indicates a higher level of inflammation.
- A blood sample is drawn from a vein, typically in your arm.
- The sample is placed in a tall, thin test tube.
- The time it takes for the red blood cells to settle is measured, usually in millimeters per hour (mm/hr).
What the Results Mean
A high ESR doesn't pinpoint a specific condition but suggests the presence of inflammation. Possible causes of elevated ESR include:
- Infections: Bacterial, viral, or fungal infections.
- Autoimmune diseases: Rheumatoid arthritis, lupus, etc.
- Cancers: Some types of cancer can cause inflammation.
- Other inflammatory conditions: Polymyalgia rheumatica, temporal arteritis, etc.
- Pregnancy: ESR levels can naturally increase during pregnancy.
A normal ESR can rule out inflammation, but further tests may be necessary for a definitive diagnosis. A low ESR typically indicates little to no inflammation. The interpretation of ESR results should always be done in conjunction with other clinical findings and test results.
Why is an ESR Test Ordered?
Doctors order ESR tests to:
- Help diagnose and monitor inflammatory conditions.
- Track the effectiveness of treatment for inflammatory diseases.
- Detect the presence of infection or other inflammatory processes.
It's important to note: The ESR test is not specific to any one disease. It's a non-specific marker of inflammation. Other tests are needed for accurate diagnosis.
