A Correlation of Prothrombin Time in Citrated Specimens and EDTA Specimens Examined by Owren Method

Ahn, Je Joon; Park, Joo Won

Abstract

BACKGROUND: Sodium citrate has been used as a coagulation test because factor V and VIII are more stable in a citrated specimen. Ethylenediaminetetraacetic acid (EDTA) has been used for the hematologic test because blood cells are preserved better in the EDTA specimen. Both sodium cit-rate and EDTA have the same principle of anticoagulation. They bind free plasma calcium to pre-vent clotting. This study was performed to see if we could substitute EDTA for sodium citrate in pro-thrombin time.
METHODS
Blood samples from 133 patients who underwent the prothrombin time test in our hos-pital and 36 healthy controls were used. Each sample was anticoagulated with both sodium citrate and EDTA. We examined the prothrombin time with citrated specimen and EDTA specimen using the Owren reagent; Nycotest PT and also the Quick reagent; and the IL Test PT-Fibrinogen HS.
RESULTS
The mean prothrombin time with EDTA specimen was longer than that with the citrated specimen by the Quick method but was shorter using the Owren method. In the Owren method, there was a significant correlation between mean prothrombin time with the citrated and EDTA spec-imen but not using the Quick method.
CONCLUSIONS
The prothrombin time with the citrated and EDTA specimens correlated with each other by the Owren method. This correlation could make it possible to replace sodium citrate with EDTA.