An Erythrocyte Sedimentation Rate (ESR) test is collected in which tube?

The Erythrocyte Sedimentation Rate (ESR) test is collected in a tube with a lavender top because this tube typically contains EDTA (ethylenediaminetetraacetic acid), an anticoagulant that prevents the blood from clotting. The presence of EDTA is crucial for the ESR test, as it measures how quickly red blood cells settle at the bottom of a test tube over a specified period. This settling is influenced by factors such as plasma proteins and is utilized to detect inflammation and autoimmune disorders.

Using a tube without an appropriate anticoagulant or with a different additive could lead to inaccurate results or affect the test's efficacy. Therefore, the lavender tube is specifically designed for tests that require whole blood or are sensitive to the effects of clotting. This makes it the correct choice for the ESR test.