What does the ESR test measure?

The ESR test, or erythrocyte sedimentation rate test, specifically measures the distance that red blood cells (erythrocytes) settle in a sample of blood over a defined period, typically one hour. This measurement reflects the presence of inflammation in the body. When inflammation occurs, proteins in the blood increase, causing red blood cells to clump together and settle more quickly. Therefore, a higher sedimentation rate may indicate inflammatory conditions, infections, or other diseases, making this test a useful diagnostic tool.

In contrast, measuring glucose levels pertains to different tests such as a fasting blood glucose or glucose tolerance test, which is unrelated to the ESR. The rate of oxygen in the blood is assessed with tests like arterial blood gases but is not associated with the ESR. Lastly, the detection of abnormal cells is typically done through other methods, such as a pap smear or biopsy, rather than the ESR test, which focuses solely on sedimentation of red blood cells.