The Use of a Stabilized Partial Thromboplastin Reagent in the Partial Thromboplastin Test.

1THE PARTIAL THROMBOPLASTIN TIME test was originally developed by Langdell et al. (1) as a method of following the therapy of hemophulic patients. These investigators found this test to be extremely sensitive to changes in Factor VIII brought about by whole blood or plasma transfusions. Extensive studies of the partial thromboplastin time test (PTT) by Rodman et il. (2) have shown that this test is sensitive to plasma deficiencies of Factor II (prothrombin), Factor V (AcG, labile factor), Factor VIII, Factor IX (PTC), Factor X (Stuart Prower factor), Factor XI (PTA), and Factor XII (Hageman factor). In patients deficient in any of the above factors, prolonged PTT values are obtained. However, the partial thromboplastin test is not sensitive to plasmas that are deficient only in Factor VII (SPCA, Proconvertmn). If a patient’s Factor VII deficient plasma has a concomitant deficiency of any of the other plasma coagulation factors, a prolonged PTT will be found. The purpose of this paper is to report some of the properties of and results obtained with a standardized, stabilized partial thromboplastin reagent (PTR).*