A COMPARISON OF LYOPHILIZED ARTIFICIALLY DEPLETED PLASMAS AND LYOPHILIZED PLASMAS FROM PATIENTS RECEIVING WARFARIN IN CORRECTING FOR COAGULOMETER EFFECTS ON INTERNATIONAL NORMALIZED RATIOS

The comparative value of lyophilized artificially depleted plasmas and plasmas from warfarin-treated patients in local (thromboplastin/coagu lometer) system International Sensitivity Indices (ISI) determination has been studied at 39 centers in an international collaborative study . At each center, both types of plasmas were tested with two common th romboplastins (low ISI RecombiPlasTin and high ISI OBT), and in-house reagents using three brands of coagulometers. In 95 local systems, the y was agreement. With both thromboplastins, coagulometers lowered the ISI from the manual or stated ISI with all systems. Differences betwee n the two types of lyophilized plasmas with the two common thromboplas tins were not of clinical importance. Artificially depleted plasmas ar e easier to obtain in sufficient volumes than plasma from, warfarin-tr eated patients, nod more easily provide the wide range of INR values r equired for reliable local ISI calibration. The agreement between the two types of lyophilized calibrant is reassuring.