The reference plasma standard is plotted in red. The graph shows the results of the Factor VIII assays. Click HERE for a pdf of Log-Lin graph paper. The clotting time for each dilution is shown in seconds.
The data below will allow you to plot a number of factor VIII assays. There is data that analysing Thrombin Generation in patients with Factor XI deficiency can be of value in establishing their bleeding phenotype - see References.įailure to obtain a straight line or non-parallel lines when plotting the APTT/dilution of the test sample may indicate the presence of an inhibitor. In Factor XI deficiency the bleeding risk varies between individuals with the same Factor level but is consistent for a given individual. The factor deficient plasma should have a level of the factor being assayed of 0.01 IU/mL ] but <0.05 IU/mL ]įactor VIII or IX is 0.05-0.30 IU/mL ]
The reference plasma is used to derive the concentration of the test plasma by comparing the clotting times.Ĭommercial reference standards in which the levels of the clotting clotting factors, are calibrated against international standards and their levels are reported in IU/dl or IU/ml and not %.įactor deficient plasma (substrate plasma)Ī plasma deficient in the clotting factor to be assayed - most commonly VIII, IX, or XI. The reagents used in the assay are summarised below: Reagents
PL: Synthetic Phospholipid used to replace platelet-derived phospholipid as assays are performed on Platelet Poor Plasma. In the case of an APTT-based assay, this is commonly Silica, Ellagic Acid or less frequently Kaolin. Activator: Depends upon whether the APTT or the PT test is being used for the specific assay.
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