What are the diagnostic criteria for Polycythemia Vera (PV), a myeloproliferative neoplasm (MPN)?

From the Guidelines

Diagnosing polycythemia vera requires a comprehensive approach that includes blood tests, bone marrow examination, and genetic testing, with the presence of elevated hemoglobin/hematocrit or increased red cell mass, bone marrow findings consistent with polycythemia vera, and presence of JAK2 mutation, with low serum erythropoietin as a minor criterion, as per the World Health Organization diagnostic criteria 1. The diagnosis begins with a complete blood count showing elevated hemoglobin and hematocrit, often accompanied by increased red blood cell mass.

• Key findings include:
  • Elevated hemoglobin (>16.5 g/dL in men, >16.0 g/dL in women)
  • Elevated hematocrit (>49% in men, >48% in women)
  • Increased red blood cell mass
• Testing for the JAK2 V617F mutation is crucial, as it's present in approximately 95% of polycythemia vera cases; if negative, testing for JAK2 exon 12 mutations should follow 1.
• A bone marrow biopsy showing hypercellularity with trilineage growth (erythroid, granulocytic, and megakaryocytic) helps confirm the diagnosis.
• Serum erythropoietin levels are typically low or normal, which helps distinguish polycythemia vera from secondary polycythemia where levels are elevated.
• Additional findings may include leukocytosis, thrombocytosis, splenomegaly, and pruritus, particularly after bathing.
• Excluding secondary causes of erythrocytosis such as hypoxia, smoking, or kidney disease is essential for accurate diagnosis 1.

From the Research

Diagnostic Criteria for Polycythemia Vera (PV)

The diagnostic criteria for Polycythemia Vera (PV) include:

• Hemoglobin/hematocrit levels of >16.5 g/dL/49% in men or 16 g/dL/48% in women 2
• Presence of a JAK2 mutation 2, 3, 4
• Morphologic confirmation by bone marrow examination, although not mandated 2
• Absence of causes of secondary erythrocytosis 5

Laboratory Tests

Laboratory tests used to diagnose PV include:

• Serum erythropoietin level, which is typically low-normal in PV patients 5
• JAK2 mutation testing, which is positive in most PV patients 2, 3, 4
• Bone marrow biopsy, which can help distinguish PV from other myeloproliferative neoplasms (MPNs) 6
• Cytogenetic analysis, which can detect abnormal karyotypes in some PV patients 2

Clinical Features

Clinical features that support a diagnosis of PV include:

• Erythrocytosis, which is a hallmark of the disease 5, 2
• Leukocytosis and thrombocytosis, which are common in PV patients 5, 2
• Splenomegaly, which is present in some PV patients 5, 2
• Pruritus, constitutional symptoms, and microcirculatory disturbances, which can occur in PV patients 2