The instrument manufacturer has provided reference ranges for three anticoagulants; lithium heparin (typically a green top blood collection tube), 3.2 % citrate (typically a blue top blood collection tube), and an RUO hirudin blood collection tube (3 mL) available from the instrument manufacturer. With the hirudin whole blood, the hirudin concentration in whole blood is >15 ug/mL. Note that the ACD blood collection tube (typically a yellow top blood collection tube) is not suitable for platelet function testing as low pH inhibits platelet function. Other anticoagulants require user validation for their suitability.