Final answer:
The erythrocyte sedimentation rate (ESR) is a blood test used to diagnose rheumatoid arthritis (RA). It measures how quickly red blood cells settle to the bottom of a test tube over time. The ESR test is not specific to RA and is usually used in combination with other tests to confirm the diagnosis.
Step-by-step explanation:
The erythrocyte sedimentation rate (ESR)is a blood test used to help diagnose rheumatoid arthritis (RA), an autoimmune disease that affects the joints. The ESR test measures how quickly red blood cells settle to the bottom of a test tube over a period of time. The results are reported as a rate in millimeters per hour (mm/h).
The ESR test is not specific to RA and can be elevated in other inflammatory conditions as well. Therefore, it is usually used in combination with other tests, such as rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibodies, and C-reactive protein (CRP), to help confirm the diagnosis of RA.
The ESR test does not vary greatly between genders or as people age. However, the normal range for ESR may vary slightly depending on the laboratory and the method used to perform the test.