Laboratory monitoring of heparin therapy--the effect of different salts of heparin on the activated partial thromboplastin time.

Data from the 1978 CAP Hematology Survey were analyzed for the effect of sodium and calcium salts of heparin on the activated partial thromboplastin time (APTT). The results indicate that the sodium salt of heparin prolongs the APTT more than the calcium salt at a heparin concentration of 0.2 units/ml. Furthermore, there was a variable response of the different APTT reagents to the different heparin salts. Data from the 1979 CAP Hematology Survey showed a greater sensitivity of the Automated APTT reagent and the Platelin Plus Activator of General Diagnostics compared with Actin (Dade) and Thrombofax (Ortho) at therapeutic heparin levels of 0.2 units/ml to 0.4 units/ml. The 1979 CAP heparin questionnaire results are presented and analyzed.