Determination of heparin levels in blood with activated partial thromboplastin time by a piezoelectric quartz crystal sensor

A piezoelectric quartz crystal (PQC) sensor, possessing a sensitive frequen cy response to viscoelastic variations of substance loading on an electrode surface, was used to determine both whole blood activated partial thrombop lastin time (WBaPTT) and plasma activated partial thromboplastin time (PLaP TT) induced by anticoagulant heparin. The PQC sensor results showed a linea r relationship between WBaPTT (or PLaPTT) and heparin levels in clinically relevant concentrations (0-0.4 unit/ml). Mean of individual R-2 (= 0.9491) for a regressive curve between WBaPTT and heparin concentrations was adequa tely shown. The PQC method can be used to evaluate the effect of heparin th rough determination of WBaPTT owing to comparable sensitivity (P < 0.01) wi th that of aPTT by optical coagulometry (OCaPTT). Furthermore, we found the results of WBaPTT with various heparin concentrations (n = 9) to be well c orrelated with those of OCaPTT (correlation coefficient = 0.9441). Linear c alibration plots were extended into 3 units/ml of heparin in PLaPTT and WBa PTT. It was suggested that the PQC method will provide a more convenient op eration, may be useful in clinical situations for rapid monitoring heparin therapy using small volume (20 <mu>l) of whole blood specimens. (C) 2001 El sevier Science B.V. All rights reserved.