ESR stands for erythrocyte sedimentation rate, which is a blood test that measures how quickly red blood cells settle at the bottom of a test tube over a specified period of time. The rate at which red blood cells settle is influenced by a number of factors, including the presence of certain proteins in the blood, which can cause the red blood cells to clump together and settle more quickly.
The rate at which ESR rises can vary depending on the underlying cause of the increase. In general, ESR tends to rise more slowly than other markers of inflammation, such as C-reactive protein (CRP). ESR may take several days to increase in response to an inflammatory condition, and it may continue to rise for several weeks before reaching its peak.
It is important to note that ESR is a non-specific marker of inflammation, meaning that an increase in ESR alone cannot be used to diagnose a specific condition. Additional tests and a thorough medical evaluation are typically needed to determine the underlying cause of an elevated ESR level.