Which additive is used in the Light Green tube?

The correct answer is lithium heparin, which is the additive found in light green tubes. This additive acts as an anticoagulant, preventing blood from clotting by inhibiting thrombin and factor Xa, which are essential for the coagulation process. This characteristic makes lithium heparin particularly useful for certain tests that require plasma, such as chemistry panels, where a quick turnaround of results is desired.

Light green tubes are specifically designed for assays that will benefit from the rapid processing of plasma samples. Because lithium heparin provides effective anticoagulation without significantly interfering with the majority of laboratory tests, it is a common choice in clinical settings for various biochemical analyses.

The distinction between lithium heparin and other additives, such as sodium heparin or various forms of EDTA, lies primarily in the chemical composition and the specific tests they are suited for, which highlights the importance of selecting the correct tube type based on the requirements of the laboratory test being performed.