[Laboratory control of oral anticoagulation].
BACKGROUND
The authors verified the performance of three different thromboplastin preparations, commercially available to Brazilian clinical laboratories, on the anticoagulant level monitoring of anti-vitamin K drugs.


METHODS
Thromboplastin preparations included: Labtest, lot n degrees 0301, ISI = 1.50; Biolab, lot n degrees 10252, ISI = 1.60; Baxter TPCD, lot n degrees 502A, ISI = 2.55; Baxter TPC, lot n degrees 13, ISI = 1.97; Baxter TPS, lot n degrees 27, ISI = 1.18; and Behring, lot n degrees 505771A, ISI = 1.11. Thirty-one outpatients with thromboembolism were evaluated. All patients were taking the same dose of anti-vitamin K drugs for at least 10 days.


METHODS
Laboratorial monitoring has been undertaken by the measurement of Prothrombin Time (TP). A standard curve was obtained for each reagent, using a normal plasma pool. Results were expressed as PT in seconds, and as prothrombin activity (PA) in percentage, according to the standard curve, and also as the International Normalized Ratio (INR), calculated using the International Sensitivity Index (ISI) provided by each reagent producer.


RESULTS
There was some discrepancy among results obtained with different reagents, when these results were expressed as PA (p < 0.01), but this effect was minimized when they were expressed as INR.


CONCLUSIONS
This fact confirms that results of PT, performed in order to control the action of anti-vitamin K drugs, must be reported as INR to assure reproducibility among tests performed using different thromboplastin reagents, with different ISI.
Disciplina de Hematologia e Hemoterapia, Escola Paulista de Medicina, São Paulo.
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Alves
D000925:Anticoagulants / Q000097:blood* / Q000627:therapeutic use; D001777:Blood Coagulation / Q000502:physiology; D006490:Hemostatics / Q000037:antagonists & inhibitors; D006801:Humans; D011516:Prothrombin / Q000187:drug effects; D011517:Prothrombin Time; D012680:Sensitivity and Specificity; D013925:Thromboplastin; D013927:Thrombosis / Q000517:prevention & control; D014812:Vitamin K / Q000037:antagonists & inhibitors
D000925:Anticoagulants; D006490:Hemostatics; D014812:Vitamin K; D011516:Prothrombin; D013925:Thromboplastin
Controle laboratorial da anticoagulação oral.