Correlation Between PT and INR to Factor 7

Factor VII is one of the main components of the coagulation process. It belongs to the serine proteases and it dependents on vitamin K in order to function. Its primary function is to initiate the clotting process itself, along with tissue factor: Following a vascular endothelial injury, there is a response of vasoconstriction, the blood flow in contact with the subendothelial matrix, at that time, TF, a protein in the same matrix, binds to and activates the VII coagulation factor, then, FVIIa-TF complex begins the coagulation cascade, at the end of that cascade, fibrin is formed.

The factor VII gene is located on the long arm of chromosome 13, sized 12 kD, contains 12 axons that encode a protein composed of 406 amino acids, it's located at a distance of 2.8 kD from the gene of factor X.

More than 120 mutations have been found in factor VII gene to date, the association between genotype and phenotypes is unclear in most cases however. Seligsohn and his colleagues described one of the mutations in Factor VII, 5-Ser339Phe, which was found in three Tunisian families and caused a tendency to bleed through a mechanism of reduced factor X activation.

When it comes to Factor VII deficiency, the missing is never hermetic as such condition is not compatible with life as seen from work on knockout mice. Partially missing factor VII is the most common of all rare coagulation problems. Clinically, these are usually epistaxis, easy bruising, gum bleeding, muscle hematoma, hamarhtrosis, hematuria, postoperative bleeding, although there may also be conditions of life threatening blood in the nervous system and in the gastrointestinal tract. Except for increased menstruation that occurs in about 70% of the women with factor VII deficiency, there is no gender difference in symptoms.

Suspicion of Factor VII deficiency is usually done in the course of screening in family members with a known deficiency or on tests following an episode of bleeding, such as epistaxis or surgery in areas with a tendency to bleed (nose, throat or teeth) .

An abnormal PT test indicates a lack of factor VII. An elongated PTT test can suggest hemophilia A and B (missing factors VIII and IX, respectively), lack of factor XI, incomplete factor XII or von disease willebrand / VWF . The extension of PT also implies a deficiency in the factors X, V, II and fibrinogen, and the result is represented by a percentage relative to normal people.

The diagnosis of Factor VII deficiency is laboratory. The initial laboratory tests are PT, aPTT and platelet count, followed by a FVII coagulant activity test for prolonged PT states. In order to confirm the result, the FVII assay is performed again

Prothrombin time is typically analyzed by a laboratory technologist on an automated instrument at 37 °C. Blood is drawn into a test tube containing liquid sodium citrate, which acts as an anticoagulant by binding the calcium in a sample. The blood is mixed, then centrifuged to separate blood cells from plasma (as prothrombin time is most commonly measured using blood plasma). A sample of the plasma is extracted from the test tube and placed into a measuring test tube Next an excess of calcium is added to the test tube, thereby reversing the effects of citrate and enabling the blood to clot again. Finally, in order to activate the extrinsic / tissue factor clotting cascade pathway, tissue factor is added and the time the sample takes to clot is measured optically. The prothrombin ratio (INR) is the prothrombin time for a patient sample divided by the result for control plasma.

There are two types of Factor VII deficiency. The first is a quantitative with both a lack of FVII coagulant activity and with a low level of FVII antigen, the second one is qualitative with a low FVII coagulant activity but a normal level of FVII antigen. In fact, the examination of the antigen distinguishes between these two missing types, but does not predict the tendency to bleed, and it is not recommended to diagnose Factor VII deficiency on the basis of the antigen test. However, for known patients receiving a recombinant factor it can be useful.

There are no clear guidelines for the treatment of hereditary deficiency VII. Recombinant factor VII is a choice in many cases for both children and adults, but there are other treatment options as discussed in our study.

The purpose of the current study is to find a correlation between the value of PT\INR and the level of factor VII, we tried to do so by a retro-prospective study on patients known to have a factor VII deficiency at Laniado hospital, such a correlation could make both the diagnosis and the management of people with factor VII deficiency easier and more accessible.