Critical aspects in routine coagulation testing

Abstract

The major improvements obtained in the quality of commercial reagents and in the accuracy of coagulometers has rendered comparabilty of the results among different laboratories a major task of the bodies devoted to standardization of coagulation testing. Commutability of results is of major importance especially in the monitoring of anticoagulant therapy. Critical aspects relate to the preanalytical phase, the anaytical phase and to the expression of results with the adoption of proper correction factors - like the international sensitivity index (ISI) for thromboplastin reagents. Problems with the APTT in the monitoring of heparin treatment include the variable sensitivity of commercially available APTT reagents to clinically insignificant deficiencies of factors involved in the contact phase of coagulation and to the presence of lupus anticoagulants, which - in addition to the different sensitivity of the reagents to the anticoagulant effect of heparin - render commutability of results unworkable in practice.