These are the green-top tubes, widely used for biochemistry tests because they prevent clotting without interfering much with analytes.
Key details:
Additive: Lithium heparin
Action: Inhibits thrombin → prevents clot formation
Sample type: Plasma
Mixing: Gently invert 5–8 times
Common tests:
Routine biochemistry (Urea, Creatinine, LFTs, Electrolytes*)
Cardiac markers (Troponin, CK-MB)
CRP, Procalcitonin
Ammonia (urgent samples)
Blood gases (specific heparinized tubes)