LABORATORY CONTROL OF ANTICOAGULATION THERAPY; QUALITY CONTROL IN COAGULATION PROCEDURES IN ONE-STAGE PROTHROMBIN TIME.
SCHOOL OF AEROSPACE MEDICINE BROOKS AFB TEX
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The study involved a comparison of 0.1 M sodium oxalate and 3.8 sodium citrate as plasma decalcifying agents for use with the one-stage prothrombin time. Samples of blood were drawn from 10 normal humans and 10 patients on long-term, coumarin-derivative therapy. One-stage prothrombin determinations were made on stoppered and unstoppered samples incubated at 4, 27, and 37C. after 4 hours of incubation. Factor V and Factor VII were added to the specimens after incubation, and a prothrombin determination was made. Factor V activity began decreasing as early as 15 minutes after the specimen was drawn and was rapidly and progressively decreased in samples decalcified with 0.1 M sodium oxalate, resulting in an increase in the prothrombin time. In contrast, 3.8 sodium citrate seemed to stabilize Factor V and is recommended for routine use as the plasma decalcifying agent of choice in the performance of the one-stage prothrombin time. Author