What additive is found in a dark green top tube?

The dark green top tube contains sodium heparin as its additive. This anticoagulant works by inhibiting thrombin and factor Xa, which are crucial in the coagulation cascade. As a result, sodium heparin is effective in preventing the formation of blood clots in the sample, making it suitable for various tests that require plasma, such as certain chemistry panels and in situations where immediate analysis is necessary.

Sodium citrate, found in light blue top tubes, is used for coagulation studies but not found in dark green tubes. Sodium fluoride and potassium oxalate are additives in gray top tubes, primarily used for glucose testing to preserve the sample and inhibit glycolysis. Gel activators, common in tubes with a gold or red/gray mottled top, serve to separate serum from clotted blood but are not associated with dark green top tubes. Understanding these distinctions is essential for mastering the order of draw and ensuring accurate laboratory results.