Diagnostic Criteria for Polycythemia Vera

Primary Triggers for Investigation

A sustained increase of ≥2 g/dL hemoglobin from baseline that cannot be attributed to iron deficiency correction requires investigation, even if values remain within normal reference ranges, as per the guidelines from Blood journal 1, 2
Values above the 99th percentile for age, sex, and altitude-adjusted reference ranges mandate workup, according to the Blood journal guidelines 1, 2

Dehydration is the most common cause of falsely elevated hematocrit, and verifying adequate hydration status is crucial before proceeding with a polycythemia vera workup, as recommended by Praxis Medical Insights 3
Low MCHC (<32%) suggests iron deficiency, which can mask true erythrocytosis, and checking serum ferritin, iron studies, and transferrin saturation is necessary if MCHC is low, as suggested by Praxis Medical Insights 3

JAK2V617F (exon 14) mutation testing is first-line, and if negative, proceeding to JAK2 exon 12 mutation testing is recommended, according to Praxis Medical Insights 4
Low EPO has >90% specificity for PV, but normal EPO does not exclude PV, and high EPO suggests secondary polycythemia, as stated by Praxis Medical Insights 5
Bone marrow examination is recommended when diagnosis is suspected, particularly before initiating cytoreductive therapy, and should include looking for hypercellularity for age with trilineage growth, as recommended by the Journal of the National Comprehensive Cancer Network and Blood journal 6, 1, 2

Diagnosis requires BOTH major criteria plus 1 minor criterion, OR the first major criterion plus 2 minor criteria, including hemoglobin ≥18.5 g/dL (men) or ≥16.5 g/dL (women), presence of JAK2V617F or JAK2 exon 12 mutation, bone marrow biopsy showing hypercellularity with trilineage growth, serum erythropoietin below normal reference range, and endogenous erythroid colony formation in vitro, as defined by the Blood journal guidelines 1, 2

The American Society of Hematology recommends that a diagnosis of polycythemia vera be considered in patients with hemoglobin elevation to ≥18.5 g/dL in men or ≥16.5 g/dL in women, and hematocrit elevation to ≥49% in men or ≥48% in women 7, 8
A sustained increase of ≥2 g/dL hemoglobin from baseline, even if values remain within normal reference ranges, should trigger investigation for polycythemia vera, according to the National Comprehensive Cancer Network 7

The American College of Clinical Oncology notes that leukocytosis is present in approximately 49% of polycythemia vera patients at diagnosis, with white blood cell count often elevated, typically >10 × 10⁹/L 9
Leukocytosis >15 × 10⁹/L is a risk factor for inferior survival and increased thrombotic risk, as reported by the Mayo Clinic 10
The differential typically shows increased neutrophils without significant left shift, according to the American Society of Hematology 8

The American College of Clinical Oncology states that platelet counts are frequently elevated, often >400 × 10⁹/L, in patients with polycythemia vera 9
Platelet counts >1,500 × 10⁹/L indicate need for cytoreductive therapy, as recommended by the National Comprehensive Cancer Network 9
Extreme thrombocytosis (≥1,000 × 10⁹/L) paradoxically increases bleeding risk due to acquired von Willebrand disease, according to the Mayo Clinic 10

The American Society of Hematology recommends that JAK2 mutation testing, present in >95% of polycythemia vera cases, is essential for diagnosis 7, 8
Bone marrow biopsy showing hypercellularity with trilineage growth (panmyelosis) confirms the diagnosis of polycythemia vera, as reported by the American Society of Hematology 7, 8