CRITICAL ASPECTS IN ROUTINE COAGULATION-TESTING

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 devote d to standardization of coagulation testing. Commutability of results is of major importance especially in the monitoring of anticoagulant t herapy. Critical aspects relate to the preanalytical phase, the anayti cal phase and to the expression of results with the adoption of proper correction factors - like the international sensitivity index (ISI) f or thromboplastin reagents. Problems with the APTT in the monitoring o f heparin treatment include the variable sensitivity of commercially a vailable APTT reagents to clinically insignificant deficiencies of fac tors involved in the contact phase of coagulation and to the presence of lupus anticoagulants, which - in addition to the different sensitiv ity of the reagents to the anticoagulant effect of heparin - render co mmutability of results unworkable in practice.