Applikation photometrischer Tests zur Bestimmung von Thromboplastinzeit (TPZ), aktivierter partieller Thromboplastinzeit (aPTT) und Fibrinogen an den Analysenautomaten Gem-Profiler

Abstract

The application ofthe routine coagulation parameters thromboplastin time (TPZ), activated partial thromboplastin time (aPTT) and fibrinogen to the Gern-ProfHer centrifugalanalyzer ispresented. Instead of detection of the first fibrin Strands during clotting äs a measurement point, the photometric TPZ and aPTT methods relies on the measurement of the colored product p-nitroanilin at 405 nm. This colored product is cleaved out of the chromogenic Substrate by thrombin activated through the coagulation cascade. The kinetic assay for fibrinogen is based on aggregation of des-A-fibrin to fibrin S following proteolytic cleavage of fibrinogen with a solution of the thrombin-like snake venom batroxobin. Clotting velocity is recorded turbidimetrically at340nm, For the photometric coagulation tests coefficients of Variation from 0.7 to 4.8% within run and from 1.5 to 6.1% from day to day in control samples in the normal and abnormal ränge are comparable to that of mechanised assays of clinical chemistry. The correlations between the photometric and the coagulometric methods in a heterogenous patient group showed good agreements of the methods (r = 0.91-0.97). Lipemic specimens, hemolysis and bilirubin do notinterfere with fibrinogen determinations whereas bilirubin levels higher than 400 / Interrupt the measurement of TPZ and aPTT. The advantages of the photometric TPZ-and aPTTmethods are: fibrinogen-independent measurement, very good precision, easy performänce f 1 Electro Nucleonics International, Stuttgart. 232Lab.med. 12: 232 (1988) Brought to you by | University of Queensland -UQ Library Authenticated Download Date | 7/13/15 2:11 AM standardization and automatisation (sample throughput of 120-160/h). The mean features of the kinetic turbidimetric method for determination offunctional fibrinogen in comparison to the Clauss-technique are the broad measuring ränge without necessary sample dilutions, the better reliability and the Iower interference by fibrin/fibrinogen degradation products.

Evaluation of a Prothrombin Time Optimized for the Dog on Plasmas with Defined Coagulation Factor Deficiency Due to Coumarin Intoxication

“…The coefficients of variation of the optimized method for measurements in a series (0.81-3.02 "/ . ) or on different days (4.44-5.29 %) fulfil the demands made on the quality of a routine test in a human laboratory (RATGE and WISSER, 1988).…”