What does SED rate measure in a blood test?

The sedimentation rate, commonly referred to as the SED rate or erythrocyte sedimentation rate (ESR), specifically measures the rate at which red blood cells settle in a period of one hour. This test is utilized primarily to detect inflammation in the body. When inflammation is present, certain proteins such as fibrinogen can cause red blood cells to clump together, leading them to settle faster than normal. Thus, an elevated SED rate can suggest an underlying inflammatory condition, but it is not specific to the type of inflammation or the disease causing it. This makes it a useful screening tool rather than a definitive diagnostic test.

The other options pertain to unrelated measurements, which do not align with the function of the SED rate. For instance, the presence of antibodies is determined through different immunological assays, while glucose levels are evaluated through specific tests such as blood glucose tests. Electrolyte concentrations are measured through another set of biochemical tests designed to assess levels of substances like sodium, potassium, and chloride in the blood.