Which tube is used for serum testing and is drawn after the red plastic tube?

The gold, tiger, or marble tube is the correct choice for serum testing after the red plastic tube. This type of tube contains a serum separation gel that facilitates the separation of serum from the formed elements of blood after centrifugation. When blood is collected in a red plastic tube, the serum is allowed to clot, and once centrifuged, the liquid serum can be easily separated for various tests.

This step is particularly pertinent in serum testing because many laboratory tests require serum rather than whole blood to analyze various biomarkers, hormones, or antibodies. The specific formulation of the gold/tiger/marble tube enhances the reliability and efficacy of the serum collection process, ensuring optimal conditions for accurate laboratory assessment. Other tubes listed, while used for different purposes, do not provide the separation capabilities essential for efficient serum analysis following the collection in a red plastic tube.