Table Investigations for thrombophilia. Cases 1 and 2 had evidence of lupus anticoagulant, as demonstrated by a prolonged dilute Russell's viper venom time (DRVVT) which corrected on the addition of platelet phospholipid (DRVVT(PN)). Case 1 had, in addition, raised IgG anticardiolipin antibodies and case 3 a reduction in free protein S. APCR = activated protein C resistance.

Case 1 Case 2Case 3Normal range
Protein C (IU/ml) 0.96 1.00 1.37 0.67–1.38
Protein S antigen, total (IU/ml) 1.02 1.32 0.81 0.64–1.54
Protein S antigen, free (IU/ml) 0.71 1.34 0.55 0.61–1.43
Antithrombin (IU/ml) 0.89 1.02 0.92 0.80–1.20
Anticardiolipin IgG (g/l)55.4 1.9<5.0<8.0
Anticardiolipin IgM (mg/l) 0 0.2 8.3<11.0
DRVVT ratio 1.24 1.13 0.86 0.90–1.09
DRVVT(PN) ratio 1.12 1.03
Kaolin clotting time ratio 0.8 1.04 1.03<1.10
APCR 2.6>3.6not done>2.0
Factor V Leidennegativenegativenegativenegative