Mixing study with factor V deficient plasma and coagulation factor assay
revealed markedly reduced plasma factor V clotting activity.
Diagnosis was made on the basis of history, physical examination and laboratory investigations such as bleeding time (BT), Prothrombin time (PT), Activated Partial Thromboplastin Time (APTT),correction studies and wherever possible specific coagulation factor assay
. Correction or mixing studies using pooled normal plasma (PNP) was done to identify the prolongation of coagulation time due to factor deficiency or circulating anticoagulant inhibitors.
Specific coagulation factor assays
are required to confirm the presence of an FV inhibitor; FV activity will be decreased, often to less than 1%.
Sources of variability in coagulation factor assays
. Thromb Haemost 1987; 58:1073-7.
In future, similar study must be conducted on larger sample size in Indian population and with more precise tests such as platelet function analyzer closure time, platelet aggregation studies, prothrombin time, activated partial thromboplastin time, and coagulation factor assays
Also of note is that although coagulation factor assays
are designed to quantify factor activity levels, the assays can also detect interfering inhibitors, including LAC and inhibitors of individual factors (in which "nonparallelism" indicates the presence of an inhibitor), and therefore are an integral part of laboratory investigations of isolated aPTT prolongation, as was demonstrated in this case.
However, the effect of isocitrate on specific coagulation factor assays
has not yet been studied.