Flow cytometric analysis of autonomous growth of erythroid precursors in liquid culture detects occult polycythemia vera in the Budd-Chiari syndrome

Background/Aims: Hepatic vein thrombosis (Budd-Chiari syndrome) is associated with various hypercoagulable states, such as polycythemia vera (PV), presence of the lupus anticoagulant, paroxysmal nocturnal hemoglobinuria (PNH) and deficiencies of antithrombin III, protein C and protein S. In recent years, it has become evident that patients with the Budd-Chiari syndrome may have more than one risk factor that may cause a state of hypercoagulability. The aim of the current study was to assess the prevalence of occult PV in patients with Budd-Chiari syndrome using a novel method for the detection of spontaneous erythroid growth. Methods: Twenty-two patients with Budd-Chiari syndrome were evaluated. As controls, we studied normal donors and four patients with liver cirrhosis and five patients with right-side heart failure, two conditions that in part mimic Budd-Chiari syndrome. The presence of PV was determined by flow cytometric analysis of autonomous growth of erythroid precursors. Patients were considered as having occult PV if they had spontaneous erythroid cell growth in the absence of erythropoietin and with no features of overt PV. Results: Cells from ten patients with Budd-Chiari syndrome demonstrated spontaneous erythroid cell growth; eight patients (32%) were found to have occult PV and two patients had overt PV. None of the controls had spontaneous erythroid growth. Of the eight Budd-Chiari patients with occult PV, six had one or more additional recognized hypercoagulable states. Seven patients (32%) had protein C deficiency, six patients (27%) had activated protein C resistance, five (23%) had anti-cardiolipin antibodies, five (23%) had antithrombin III deficiency, and four patients (18%) had protein S deficiency. Three patients (14%) were homozygous to methyltetra hydrofolate reductase and ten (45.5%) were heterozygous. One patient had PNH. Overall, in 12 patients there were two or more combined risk factors. Conclusions: Using a flow cytometric analysis of autonomous growth of erythroid precursors we found a clear correlation between Budd-Chiari syndrome and occult PV.