title: Idiopathic erythrocytosis: a study of a large cohort with a long follow-up.
abstract: Idiopathic erythrocytosis (IE) is an absolute erythrocytosis with no known cause, diagnosed by exclusion of primary and secondary erythrocytosis. Familial erythrocytosis (FE) is a rare disease and as the rare patients with JAK2-wild-type polycythemia vera (PV) may be misdiagnosed as IE. We compared 78 patients with IE, 21 with FE and 136 with PV in the effort to identify simple features capable of discriminating between them. FE patients were younger at diagnosis either than IE and PV (p < 0.001); IE and FE had lower WBC, platelet counts and higher serum EPO levels, and had splenomegaly and thrombotic events less frequently than PV patients. Phlebotomies to obtain a haematocrit lower than 45 % induce platelet count increase in 70 % of PV but not in IE. Mainly in men, normal spleen, normal platelet counts and no history of thrombosis at diagnosis argue against PV; diagnosis of IE could be supported by means of a cycle of venesection to see how it affects their platelet count. No simple data capable of distinguishing between IE and FE were identified; therefore, a case of sporadic erythrocytosis in a young patient should be investigated as a possible genetic cause.
authors.affiliation: Department of Medicine-DIMED, University of Padua, Padua, Italy. marialuigia.randi@unipd.it.
authors.forename: Maria Luigia
authors.initials: ML
authors.lastname: Randi
authors.affiliation: Department of Medicine-DIMED, University of Padua, Padua, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Bertozzi
authors.affiliation: Department of Medicine-DIMED, University of Padua, Padua, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Cosi
authors.affiliation: Department of Medicine-DIMED, University of Padua, Padua, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Santarossa
authors.affiliation: Department of Medicine-DIMED, University of Padua, Padua, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Peroni
authors.affiliation: Department of Medicine-DIMED, University of Padua, Padua, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Fabris
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053614:Janus Kinase 2; D008297:Male; D008875:Middle Aged; D018962:Phlebotomy / Q000639:trends; D011086:Polycythemia / Q000151:congenital / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy*; D013927:Thrombosis / Q000175:diagnosis / Q000453:epidemiology / Q000628:therapy; D055815:Young Adult
chemical_list: C507924:JAK2 protein, human; D053614:Janus Kinase 2
keywords: Familial erythrocytosis; Idiopathic erythrocytosis; Polycythemia vera