title: Comparison of several activated partial thromboplastin time methods.
abstract: Activated partial thromboplastin times (APTT's) performed with a semi-automated electrical-conductivity type of clot timer on plasmas from patients with hepatic disease and intravascular coagulation, and on warfarin or heparin therapy, were significantly lower than when done on the same plasmas with either a manual optical method or an automated optical-endpoint instrument. Results of APTT's done on normal plasmas by the three methods were not significantly different. Substitution of different activator-phospholipid reagents resulted in some variability in results, but these differences were less than those between the different done with both the electrical clot timer and the automated optical instrument on prepared plasmas containing 5.0 or 1.0% of factor II, V, VIII, IX, OR X revealed shorter times with the electrical clot timer only in the case of factor II- and factor V-deficient plasmas. APTT's done on normal plasmas to which 0.1 or 0.3 units per ml. of heparin had been added vitro also were shorter with the electrical clot itmer than the automatic optical instrument. Prothrombin times done on normal and abnormal control plasmas and on a series of plasmas from patients on warfarin therapy showed no significant difference between the two methods.
mesh_terms: D001322:Autoanalysis / Q000295:instrumentation / Q000379:methods; D001774:Blood Chemical Analysis; D001780:Blood Coagulation Tests / Q000295:instrumentation / Q000379:methods*; D004903:Erythrocyte Aggregation / Q000097:blood; D005166:Factor V Deficiency; D005171:Factor X Deficiency; D006467:Hemophilia A; D002836:Hemophilia B; D006493:Heparin / Q000627:therapeutic use; D006863:Hydrogen-Ion Concentration; D007020:Hypoprothrombinemias; D008107:Liver Diseases / Q000097:blood; D055095:Optics and Photonics; D010743:Phospholipids; D011517:Prothrombin Time; D013925:Thromboplastin / Q000502:physiology*; D013997:Time Factors; D014859:Warfarin / Q000627:therapeutic use
chemical_list: D010743:Phospholipids; D014859:Warfarin; D006493:Heparin; D013925:Thromboplastin