Global tests of haemostasis represent several reaction steps in the physiologic process of clotting. The proportion of plasma or whole blood in the test mixture of a global test is significantly higher than in clotting factor tests. Accordingly, the influence of preanalytical variables is strong, e.g. underlying diseases or drug effects. Strict adherence to preanalytical requirements is of utmost importance. Apart form the standardized reporting of the thromboplastin time (prothrombin time) as International Normalized Ratio (INR), results are generally not comparable when generated by using different reagents or instrumentation. Multiple potential influencing factors have to be considered when interpreting the results. Only laboratory requests precisely derived from the clinical situation can yield clinically relevant conclusions.     «

Global tests of haemostasis represent several reaction steps in the physiologic process of clotting. The proportion of plasma or whole blood in the test mixture of a global test is significantly higher than in clotting factor tests. Accordingly, the influence of preanalytical variables is strong, e.g. underlying diseases or drug effects. Strict adherence to preanalytical requirements is of utmost importance. Apart form the standardized reporting of the thromboplastin time (prothrombin time) as I...     »