Which color tube is typically used for serum tests?

The red tube is typically used for serum tests because it does not contain any additives that promote coagulation. This characteristic allows blood drawn into the red tube to clot and subsequently yield serum once centrifuged. Serum is the fluid portion of the blood that remains after coagulation and is commonly used in various laboratory tests to measure substances such as hormones, enzymes, and antibodies.

In contrast, the other colored tubes contain additives that either prevent clotting or preserve blood cells, which is not suitable for tests requiring serum. For example, the blue tube contains sodium citrate, which is used for coagulation studies and requires plasma, while the green tube contains heparin, which also prevents clotting. The purple tube typically contains EDTA, which is an anticoagulant used for hematology tests that require whole blood or plasma. Therefore, the red tube’s lack of additives makes it the appropriate choice for serum tests.