Ratio of factor V activities in PT and APTT assays as a new diagnostic marker of lupus anticoagulant.
Lupus anticoagulant (LA) is an antibody that interferes with phospholipid-dependent coagulation tests. We investigated the usefulness of the ratio of factor V activity determined by the Simplastin auto test (PT assay) to factor V activity determined by the Platelin Excel LS test (APTT assay) for detection of LA in plasma samples obtained from 276 patients with haematological and non-haematological disorders and 73 healthy subjects. This ratio was significantly higher in the 15 LA-positive (4.82 +/- 3.34) than in samples from healthy subjects (1.09 +/- 0.10) and was > 1.4 in 10 of the remaining 261 patient samples. The ratio was particularly low in the 54 samples from warfarin-treated patients. These findings suggest that determination of this ratio may be useful as a routine laboratory test for detection of LA. This test requires no specific antigens and can be applied in patients receiving anticoagulants such as warfarin and heparin.
Amagai
H
H
Department of Laboratory Medicine, Gunma University School of Medicine, Maebashi, Japan.
Kanda
T
T
Shizuka
R
R
Fukumura
Y
Y
Kobayashi
I
I
D000328:Adult; D015415:Biomarkers / Q000097:blood; D005165:Factor V / Q000502:physiology*; D005189:False Positive Reactions; D005260:Female; D006402:Hematologic Diseases / Q000097:blood / Q000175:diagnosis; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D008297:Male; D009369:Neoplasms / Q000097:blood / Q000175:diagnosis; D010314:Partial Thromboplastin Time; D011517:Prothrombin Time; D014859:Warfarin / Q000627:therapeutic use
D015415:Biomarkers; D016682:Lupus Coagulation Inhibitor; D014859:Warfarin; D005165:Factor V