40 



Scientific Proceedings (62). 



First from a normal case we prepare human plasma just as we 

 prepared the oxalated plasma which is to be tested. Five drops 

 of this plasma are put into five thoroughly cleansed vials. One 

 of these serves as a control, to the second three drops of the 

 normal antithrombin is added, to the third five drops of normal 

 antithrombin; to the fourth three drops of the antithrombin that 

 is to be tested, and to the fifth five drops of this antithrombin. 

 All tubes are equalized in amount by the addition of normal salt 

 solution and the mixtures are allowed to remain in contact for 

 fifteen minutes. The plasma is then recalcified by the addition 

 of % per cent, calcium chloride, the number of drops which are 

 to be added being determined by the previous coagulability test 

 which should always precede the antithrombin test. As a rule, 



TABLE 1. 





Normal 



Antithrombin 



Test. 



Hemophilia 





Control 



3 Anti. 



5 Anti. 



3 Anti. 



5 Anti. 















2 min. 



+ 



+ 



+ 



+ 



+ 



4 " 



+ + + 



+ + + 



+ + 



+ + + 



+ + 



6 " 







+ + + 





+ + + 



8 " 



four drops is the optimal amount. However, it may be that we 

 have to add a different amount for the normal plasma than for the 

 plasma that is being tested. The time of coagulation is then 

 noted in the usual way. Table I illustrates a test of this nature. 

 It reproduces a test in a case of hemophilia and shows that there 

 was no increase of antithrombin as compared to the normal. 

 There is considered to be an excess of antithrombin if the tubes 

 to which three and five drops of antithrombin have been added, 

 are greatly delayed in coagulating, as compared to the normal. 

 The validity of this test has been determined by means of preparing 

 a solution of hirudin of a strength of 1-40,000 or 1-50,000, which 

 about equals the strength of the antithrombin in human plasma, 

 and testing this upon the normal plasma in the same way as we 

 determine human antithrombin. It will be noticed that the pro- 

 thrombin and antithrombin are not delicately balanced in the 

 blood and that even when we double the amount of antithrombin, 

 the coagulation is hardly delayed. 



