Standardization of activated protein C resistance testing: effect of residual platelets in frozen plasmas assessed by commercial and home-made methods.
We investigated 42 plasmas prepared at different centrifugation speeds with three activated protein C (APC) resistance methods. The APC ratio for fresh platelet-poor plasma declined significantly after freezing and thawing. This effect was more evident with the original method (average reduction 11.3%) than with either the home-made (3.8%) or the modified method (3.2%). No significant decrease in the APC ratio was observed after freezing and thawing of platelet-free plasmas from the same patients. When frozen platelet-poor plasma was centrifuged at high speed after thawing and before testing, there was no significant decrease in the APC ratio, in comparison with fresh platelet-poor plasma using the home-made and modified methods.
Tripodi
Armando
A
Angelo Bianchi Bonomi Haemophilia and Thrombosis Centre, Department of Internal Medicine, University and IRCCS Maggiore Hospital, Milan, Italy. armando.tripodi@unimi.it
Valsecchi
Carla
C
Chantarangkul
Veena
V
Battaglioli
Tullia
T
Mannucci
Pier Mannuccio
PM
D020016:Activated Protein C Resistance / Q000175:diagnosis*; D001781:Blood Component Removal; D001792:Blood Platelets; D002498:Centrifugation; D005165:Factor V / Q000235:genetics; D006579:Heterozygote; D006801:Humans; D009154:Mutation / Q000235:genetics; D010314:Partial Thromboplastin Time; D010949:Plasma / Q000737:chemistry; D011486:Protein C / Q000032:analysis; D012015:Reference Standards; D012680:Sensitivity and Specificity
D011486:Protein C; C095381:factor V Leiden; D005165:Factor V