Diagnosis and Management of Polycythemia Rubra Vera

Clinical Features and Diagnostic Criteria

The National Comprehensive Cancer Network recommends that a diagnosis of polycythemia vera (PV) be considered in patients with elevated red cell mass, aquagenic pruritus, and splenomegaly, along with a characteristic ruddy complexion 1, 2
Elevated packed red cell volume with raised cell mass is a primary major criterion for PV diagnosis, with hemoglobin >16.0 g/dL in women or hematocrit >48% in women 2
Aquagenic pruritus, occurring in approximately 48% of patients, is a non-life-threatening but characteristic complication of PV 3, 4
Palpable splenomegaly is present due to extramedullary hematopoiesis and is a common finding in PV 1
Thrombocytosis and leukocytosis indicate trilineage myeloproliferation, which is characteristic of PV 2, 5
Microvascular disturbances, such as headaches and visual disturbances, represent microvascular complications from hyperviscosity and are common presenting symptoms 4, 6
A history of gout is consistent with increased cell turnover in myeloproliferative disorders 7

The World Health Organization (WHO) 2016 criteria require either all 3 major criteria or the first 2 major criteria plus the minor criterion for a diagnosis of PV 2
Major criteria include elevated hemoglobin or hematocrit, bone marrow biopsy showing hypercellularity with trilineage growth and pleomorphic megakaryocytes, and presence of JAK2 V617F or JAK2 exon 12 mutation 1, 2
A subnormal serum erythropoietin level has a specificity >90% for PV and should be tested 5, 7
JAK2 mutation testing is essential, as it is present in >95% of PV cases and is a major diagnostic criterion 1, 2

Therapeutic phlebotomy to maintain hematocrit <45% reduces thrombosis risk 5
Low-dose aspirin 81 mg daily is recommended for all patients unless contraindicated, which also treats aquagenic pruritus and erythromelalgia 3, 4, 5
Risk stratification for cytoreductive therapy (hydroxyurea) is necessary if high-risk features are present (age >60 years or prior thrombosis) 1, 5

The disease can remain undetected for several years as erythrocytosis develops gradually, allowing patients to physiologically adapt to increasing red cell mass without recognizing symptoms 8, 9.
Median age at diagnosis is approximately 60 years, but the clonal stem cell disorder likely begins years earlier before reaching diagnostic thresholds 9.
Approximately 7% of patients are diagnosed before age 40 years, suggesting variable rates of disease progression and symptom development 9.
Incidental discovery on routine complete blood count showing elevated hemoglobin/hematocrit is the most common presentation, occurring when patients are asymptomatic or attribute vague symptoms to other causes 8, 10.

Patients physiologically compensate for gradually increasing blood viscosity, tolerating higher hematocrit levels without acute symptoms that would prompt immediate medical attention 8.
Healthcare providers may not pursue PV evaluation unless hemoglobin exceeds the 95th percentile for sex and race, or unless PV-related features accompany borderline elevations 10.
Historical data showed median survival of less than 2 years in non-phlebotomized patients, emphasizing that untreated disease progression during the undiagnosed period significantly impacts outcomes 11.
Early aggressive phlebotomy and modern supportive care have improved median survival to over 10 years, but this benefit is lost during the undiagnosed period 11.

Measure serum erythropoietin level first—low levels make PV probable, normal levels make it possible, and high levels suggest secondary polycythemia requiring alternative evaluation 10, 11.
Red cell mass measurement is rarely required in modern practice and can miss PV cases at the left tail of the distribution or when iron deficiency coexists 10.