Determination of plasma prothrombin level by Ca2+-dependent prothrombin activator (CA-1) during warfarin anticoagulation.
OBJECTIVE
The carinactivase-1 (CA-1) test is a new method for monitoring plasma prothrombin levels during warfarin anticoagulation therapy.


METHODS
A total of 192 patients were allocated to two groups. Group A patients (n = 42) were controls (no warfarin); group B patients (n = 150) received warfarin. A Ca2+-ion and Boc-Val-Pro-Arg-pNA (a chromogenic substrate for thrombin) were added to 10-fold diluted plasma, after which prothrombin was activated with CA-1. Prothrombin levels were determined by measuring the extent of p-nitoroaniline liberation.


RESULTS
The mean prothrombin level was 112.8 +/- 20.0 microg/ml in group A (Gaussian distribution), and 53.3 +/- 19.6 microg/ml in group B. In group B, correlations were found between the CA-1 test and prothrombin levels measured by prothrombin time (PT; r = 0.61, p <0. 01), PT-INR (r = 0.61, p <0.01), Thrombotest (TT; r = 0.57, p <0.01) and Hepaplastin test (HPT; r = 0.69, p <0.01).


CONCLUSIONS
The CA-1 test represents a viable method of monitoring the coagulation system. CA-1 recognized the Gla-domain of prothrombin, and activated prothrombin. The CA-1 test required only 10 microl of diluted blood plasma, and took approximately 30 min to complete. The CA-1 test also measures prothrombin levels, correlates excellently with other tests for coagulation, and compares well with currently available methods for determining the efficacy of warfarin.
Iwahashi
H
H
Department of Cardiovascular Surgery, Fukuoka University School of Medicine, Japan.
Kimura
M
M
Nakajima
K
K
Yamada
D
D
Morita
T
T
D000368:Aged; D000925:Anticoagulants / Q000097:blood*; D001681:Biological Assay / Q000379:methods; D005260:Female; D005343:Fibrinolytic Agents; D006801:Humans; D008297:Male; D008666:Metalloendopeptidases; D008875:Middle Aged; D011516:Prothrombin / Q000032:analysis*; D011517:Prothrombin Time; D015203:Reproducibility of Results; D014859:Warfarin / Q000097:blood*
D000925:Anticoagulants; D005343:Fibrinolytic Agents; D014859:Warfarin; D011516:Prothrombin; D008666:Metalloendopeptidases; C098667:carinactivase