What is typically measured in the black top tube?

The black top tube is specifically designed for measuring the erythrocyte sedimentation rate (ESR). This test evaluates how quickly red blood cells settle at the bottom of a test tube over a specified period. An increased ESR can indicate the presence of inflammation in the body, making it a useful diagnostic tool in various clinical settings.

The black top tube usually contains a reagent, such as sodium citrate or another anticoagulant, which prevents blood from clotting and allows for accurate measurement of the sedimentation rate. This contrasts with the other tests mentioned, which require different tube colors and additives. For example, heavy metals are often measured in special tubes designed to minimize contamination, coagulation factors require blue top tubes with sodium citrate, and D-dimer tests typically utilize a different anticoagulant tube, often lavender or light blue. The specification of the black top tube’s usage for ESR makes it uniquely suited to this particular test.