title: Elevated serum erythropoietin levels in patients with Budd-Chiari syndrome secondary to polycythemia vera: clinical implications for the role of JAK2 mutation analysis.
abstract: OBJECTIVE
  It is widely accepted that an increased serum endogenous erythropoietin (Epo) level in a patient presenting with an elevated red cell mass makes a diagnosis of clonal polycythemia vera (PV) extremely unlikely. However, until the recent description of the constitutively activating V617F point mutation of the Janus 2 tyrosine kinase (JAK2)--a high-frequency molecular marker that is extremely specific for clonal chronic myeloproliferative disorders--distinction of PV from secondary erythrocytosis or other conditions has often been difficult. The purpose of this study was to use JAK2 V617F analysis to re-evaluate the validity of elevated Epo levels as a PV-exclusion criterion in patients with hepatic vein thrombosis [Budd-Chiari syndrome (BCS)].
  
  
  METHODS
  We reviewed clinical data from 30 patients at our institution who presented with erythrocytosis and BCS. We isolated myeloid cells from fresh or archival bone marrow samples from four patients with BCS and an elevated serum Epo level, and analyzed them for the presence of the JAK2 V617F mutation.
  
  
  RESULTS
  All four samples were positive for JAK2 V617F, confirming the presence of a clonal hematopoietic disorder consistent with PV.
  
  
  CONCLUSIONS
  In the presence of BCS, elevated serum Epo levels do not exclude the diagnosis of PV.
authors.affiliation: Mayo Clinic College of Medicine, Rochester, MN 55905, USA. thurmes@paul@mayo.edu
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Thurmes
authors.forename: David P
authors.initials: DP
authors.lastname: Steensma
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D006502:Budd-Chiari Syndrome / Q000150:complications*; D004252:DNA Mutational Analysis; D004921:Erythropoietin / Q000097:blood*; D005260:Female; D006801:Humans; D053614:Janus Kinase 2; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D011086:Polycythemia; D011087:Polycythemia Vera / Q000175:diagnosis* / Q000209:etiology; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics*
chemical_list: D015415:Biomarkers; D011518:Proto-Oncogene Proteins; D004921:Erythropoietin; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2