DIAGNOSTIC REAGENTS 



319 



C 



o 



o 



E 



10 20 30 40 50 60 70 80 90 100 

 Per cent Prothrombin 



However, variability in prothrombin times obtained by different technicians 

 makes it imperative that the technician running the test construct a curve with 

 two or more normal plasmas using a given thromboplastin to make sure his or 

 her values correspond with the guide. Otherwise, the technician must construct 

 his own prothrombin activity curve using three or more normal human plasmas. 

 Interpretation : 



When Bacto-Thromboplastin is used in the Quick prothrombin time test, clot 

 formation is obtained in 12-14 seconds with normal plasma. The quantitative 

 relationship between the prothrombin content of plasma and its clotting time as 

 obtained by the Quick test is discussed in detail by Quick^^-^^-^^ and in the 

 "Manual for Prothrombin and Blood Clotting Determinations for Laboratory 

 Technicians" published by the Newton Health Department, Newton, Massa- 

 chusetts. 



Safe and effective limits of prothrombin activity in controlled dicoumarol 

 therapy are discussed by: Allen, Barker and Waugh,^^ Wright and Prandonij^o 

 Butsch and Stewart,^! Echstam,22 Evans,^^ Barker, Cramer, Hurn and Waugh,^* 

 Peters, Guyther and Brambel,-^ Barker, Hines, Kvale and Allen,^^ Allen^^ and 

 in leaflets descriptive of dicoumarol and its clinical application published by the 

 licensees of dicoumarol, Eli Lilly and Company,^^ Abbott Laboratories^^ and E. R. 

 Squibb and Company.^^ 



The necessity of repeated prothrombin determinations in following and deter- 

 mining the dosage in anticoagulant therapy has been emphasized by Wellman 

 and Allen.31 Bacto-Thromboplastin is eminently suited for this control procedure. 



Link-Shapiro Dilute Plasma Technique^'^'^^ 



Reagents: 



1. Thromboplastin Extract. Prepare thromboplastin extract as described for 

 the Quick technique and dilute with an equal volume of sodium chloride 

 0.85 per cent. 



