INTRAVASCULAR AND TOTAL-BODY PLATELET EQUILIBRIUM IN HEALTHY-VOLUNTEERS AND IN THROMBOCYTOPENIC PATIENTS TRANSFUSED WITH SINGLE-DONOR PLATELETS

Instrument platelet counts used in corrected count increment (CCI) and percent platelet recovery (PPR) formulas presume the transfused plate lets are in equilibrium during the first hour after platelet transfusi on, The timing of the pre-transfusion count affects CCI results, and w e postulate that timing of CCI post transfusion affects CCI results. P latelet equilibrium using indium-111 platelet transfusions has not bee n reported. Platelet redistribution was studied in 16 healthy voluntee rs and 12 thrombocytopenic patients by generally infusing less than 72 -hr stored single-donor platelets along with an aliquot of indium-111- labeled platelets by intravenous push. Counts were measured at 10, 15, 20, 60, and 120 min, and 24, 48, 72 hr along with continuous body sca nning for 2 hr in healthy volunteers, and static organ scanning in pat ients and volunteers. Results indicated transfused platelets do not re ach intravascular equilibrium for 60 min post-infusion and that the 10 -min count cannot detect platelet refractoriness, However, total body equilibrium varies considerably between normal volunteers and thromboc ytopenic patients. It is recommended to continue with the l-hr post tr ansfusion count. Am. J. Hematol, 58:165-176, 1998, (C) 1998 Wiley-Liss , Inc.