ACTIVATED PARTIAL THROMBOPLASTIN TIME AS A MONITOR OF HEPARIN THERAPY - WARNING

  • 1 January 1977
    • journal article
    • research article
    • Vol. 140  (6) , 311-315
Abstract
The degree of correlation between whole blood clotting time (WBCT) and activated partial thromboplastin time (APTT) was evaluated in 42 patients receiving intermittent i.v. heparin therapy [for deep vein thrombosis or pulmonary embolism]. Correlation between the 2 tests was poor (correlation coefficient 0.52), primarily for reasons related to characteristics of the APTT system employed. The relationship in vitro between the APTT and level of heparin was evaluated and found to vary widely over a range of heparin concentrations. The marked variability between various APTT systems and dangers involved with substituting the APTT for the WBCT to monitor heparin therapy without appropriate initial evaluation are emphasized.