Measurement of FVIII:C Level by Clot Waveform Analysis / 임상소아혈액종양

ABSTRACT

BACKGROUND: By using ACL 9000 coagulation analyzer (Instrumentation Laboratory Co., Lexington, Massachusetts, USA), we tried to investigate the possibility that activated partial thromboplastin time (aPTT) clot waveform analysis (CWA) may provide additional information on patients with hemophilia A. METHODS: Plasma samples were obtained from 35 patients with hemophilia A. The factor VIII levels of those patients were measured by a conventional one-stage factor VIIIC clotting assay and a factor VIII antigen assay. The data were applied to a Microsoft excel program calculating the index of the second derivative, and the time at point b (Min2), the point in time that clotting is initiated was also calculated. RESULTS: The corresponding aPTT clotting times were prolonged in all 9 patients with severe hemophilia A. The CWA could further discriminate between different levels of FVIIIC in the patients (n=20), with a FVIIIC level <4 IU/dL by conventional assay. The correlation between FVIIIC and the recalculated aPTT using Min2 was very high in patients with FVIIIC < or =4 IU/dL (r=0.952). Among the 9 patients who showed a lot of discrepancy from the FVIIIC level, there was 8 patients with mild hemophilia and 1 patient with moderate hemophilia (FVIIIC level 4.5%). CONCLUSION: Our study suggested that CWA and Min2 values might have greater discriminatory power in assessing low clotting factor activity. Further study is needed, including more patients with hemophilia A using CWA, correlation according to the severity group, a lower limit of detection for VIIIC, and a multiple one-stage assay.