This lab test is commonly known as the erythrocyte sedimentation rate, or ESR, and is also called the sed rate or Westergren sedimentation rate. It is a simple, inexpensive blood test that has long been used to detect the presence of acute or chronic inflammation. ESR does not identify the cause or location of inflammation; it only indicates that inflammation may be present. For this reason, it is typically interpreted alongside other laboratory tests and clinical findings. A normal ESR does not rule out inflammation, and in some cases the test is used to track changes over time. Rising ESR values may suggest that inflammation is worsening or that a treatment aimed at reducing inflammation is not effective.
ESR can be influenced by factors other than inflammation. Mild to moderate elevations may occur with anemia, infection, pregnancy, and advancing age. Certain medications, including dextran, methyldopa, oral contraceptives, penicillamine, procainamide, and theophylline, can increase ESR values, as can high vitamin A intake. Other substances, such as aspirin, cortisone, and quinine, may lower ESR levels.
