NaCitrate tubes must be filled to provide proper blood to anticoagulant ratio. Centrifuge and remove plasma with plastic transfer pipette - do not disturbe cells and Freeze immediately.
NOTE: if the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted.
Adjustment Information: High Hematocrit Samples. Patients with elevated hematocrits have a relatively low amount of plasma for a given whole blood (collection) volume. This tends to increase the plasma citrate concentration effectively. If the patient has a known hematocrit >55%, the amount of citrate in the collection tube must be decreased according to the formula below.
The equation in CLSI H21 is as follows:
C = (1.85 x 10−3) (100−Hct) (Vblood)
C is the volume of citrate remaining in the tube.
Hct is the patient's hematocrit.
V is the volume of blood added to the evacuated tube.
Patient hematocrit = 60%
Total volume = 5 mL (standard citrated plasma collection tube volume)
C = (0.00185) x (100-60) x 4.5
C = (0.00185) x 180 (or 40 x 4.5)
C = 0.333