DIRECT EVIDENCE FOR AN INCREASE IN THROMBOPOIESIS AFTER LIVER-TRANSPLANTATION

Background In advanced liver cirrhosis, thrombocytopenia results from 'hypersplenism' due to increased platelet sequestration and platelet ' pooling' in the enlarged spleen and/or from reduced platelet productio n in the bone marrow We sought to differentiate between these two mech anisms by studying thrombopoiesis before and after orthotopic liver tr ansplantation by the determination of reticulated platelets, direct in dicators for the thrombopoietic activity in the bone marrow Methods Re ticulated platelets, peripheral platelet counts, mean platelet volumes and platelet-reactive antibodies were determined in 15 patients suffe ring from advanced liver cirrhosis before and during an observation pe riod of 14 days after orthotopic liver transplantation (OLT). Thrombop oietin levels of ten patients were determined before transplantation a nd consecutively for 14 days after surgery. Results All patients excep t one were thrombocytopenic before transplantation (median count 94 x 10(9) L-1, range 69-1 14 x 10(9) L-1). Although levels of reticulated platelets rose 2 days after surgery from baseline values of 1.0% (rang e 0.2-1.6%) to peak values of 4.6% (range 1.7-17.9%, P<0.05) on day 6, platelet counts declined during the first 5 days after transplantatio n. When peripheral platelet counts increased to the normal range (medi an day 11, range day 8-33), reticulated platelets were again at pretra nsplant levels. Thrombopoietin levels before OLT were within the norma l range (< 85 pg mL(-1)). On day 5 post surgery, a maximum increase of 5.8-fold (range 2.2- to 28-fold) over baseline Values was observed. M ean platelet volume did not show any significant deviation from the ba seline values and platelet antibodies could not be detected during the observation period. Conclusion Our findings provide direct evidence f or an increase in de novo platelet production after orthotopic liver t ransplantation. As the elevation of reticulated platelets precedes pla telet recovery, it could serve as an early indicator to predict thromb opoiesis as a result of reconstituted liver function.