PV is associated with an increased risk of arterial and venous thrombosis, including around the time of diagnosis. Early recognition allows timely, guideline-based measures to reduce thrombotic risk—especially hematocrit control and low-dose aspirin when appropriate. [2,6,7]

PV is a blood cancer in which the bone marrow produces too many red blood cells (and sometimes also increases white blood cells and platelets). The increased red-cell mass can increase blood viscosity and is associated with symptoms such as headache, visual changes, aquagenic pruritus, and erythromelalgia, and with a higher risk of blood clots. [2,3,4]

Most PV is driven by acquired JAK2 mutations (most commonly JAK2 V617F, less commonly JAK2 exon 12). This is why JAK2 testing is central to modern diagnosis. [2,4]

Symptoms can be mild or intermittent, and some people are diagnosed after an abnormal CBC. Common features include:

• • Aquagenic pruritus (itching after contact with warm water). [5,9]
  • Headache, dizziness, transient visual symptoms, or other microvascular complaints
  • Fatigue/weakness (nonspecific). [2,3]
  • Splenomegaly or abdominal fullness/early satiety in some cases. [3,8]
  • Incidental lab findings (persistently high hemoglobin/hematocrit). [1,3]

Important note: these symptoms are not specific to PV. Diagnosis depends on clinical evaluation and testing. [1,3]

When hemoglobin/hematocrit is persistently high, clinicians typically:

• Confirm persistence and assess common secondary causes (hypoxia/sleep apnea, smoking/CO exposure, medications such as androgens or exogenous erythropoietin, high altitude). [3,8]
• Order JAK2 testing (V617F and, if needed, exon 12) and often serum erythropoietin (EPO) as part of the work-up. [1]
• Use bone-marrow morphology when needed for classification or when values are near diagnostic thresholds (e.g., “masked” presentations) or when distinguishing from related myeloproliferative neoplasms. [1,3,8]

Management is individualized and typically centers on

(1) reducing thrombotic risk, (2) monitoring and maintaining blood counts within clinician-defined targets, (3) addressing symptom burden and cardiovascular risk factors, and (4) long-term follow-up to watch for disease evolution or complications.

Risk assessment commonly incorporates age and prior thrombosis history as major determinants of overall thrombotic risk, with other patient-specific factors considered in shared decision-making. [3,4,10]

Many people live with PV for years to decades with ongoing care. Treatment is generally aimed at reducing complications and controlling symptoms, and regular hematology follow-up is important. [2,3]

1. How soon do I need a diagnosis?

If blood tests repeatedly show elevated hemoglobin/hematocrit or there are symptoms that raise concern, timely clinical evaluation is important because PV is associated with an increased risk of complications such as thrombosis, including around the time of diagnosis. A clinician can determine which tests are appropriate to confirm or exclude PV and to identify other causes of elevated red blood cells. [3,8]

2. What are urgent symptoms I should never ignore?

Sudden limb swelling or pain (possible DVT), chest pain, sudden breathlessness, or neurologic changes (possible stroke) require immediate emergency care. Early PV management reduces these risks but does not eliminate them. [11,12,13]

1. Arber, D. A., Orazi, A., Hasserjian, R. P., Borowitz, M. J., Calvo, K. R., Kvasnicka, H.-M., Wang, S. A., Bagg, A., … Vardiman, J. W. (2022). International Consensus Classification of myeloid neoplasms and acute leukemias: Integrating morphologic, clinical, and genomic data. Blood, 140(11), 1200–1228. https://ashpublications.org/blood/article/140/11/1200/485730/
2. Tefferi, A., Vannucchi, A. M., & Barbui, T. (2021). Polycythemia vera: Historical oversights, diagnostic details, and therapeutic views. Leukemia, 35(12), 3339–3351. https://pmc.ncbi.nlm.nih.gov/articles/PMC8632660 /
3. McMullin, M. F., Harrison, C. N., Ali, S., et al. (2019). A guideline for the diagnosis and management of polycythaemia vera: A British Society for Haematology Guideline. British Journal of Haematology, 184(2), 176–191. https://doi.org/10.1111/bjh.15648
4. Tefferi, A., & Barbui, T. (2023). Polycythemia vera: 2024 update on diagnosis, risk-stratification, and management. American Journal of Hematology, 98(9), 1465–1487. https://doi.org/10.1002/ajh.27002
5. Siegel, F. P., Tauscher, J., Petrides, P. E., & others. (2013). Aquagenic pruritus in polycythemia vera: Characteristics and influence on quality of life in 441 patients. American Journal of Hematology, 88(8), 665–669. https://doi.org/10.1002/ajh.23474
6. Marchioli, R., Finazzi, G., Specchia, G., et al. (2013). Cardiovascular events and intensity of treatment in polycythemia vera. The New England Journal of Medicine, 368(1), 22–33. https://doi.org/10.1056/NEJMoa1208500
7. Landolfi, R., Marchioli, R., Kutti, J., et al. (2004). Efficacy and safety of low-dose aspirin in polycythemia vera. The New England Journal of Medicine, 350(2), 114–124. https://doi.org/10.1056/NEJMoa035572
8. McMullin, M. F. F., Mead, A. J., Ali, S., et al. (2019). A guideline for the management of specific situations in polycythaemia vera and secondary erythrocytosis: A British Society for Haematology Guideline. British Journal of Haematology, 184(2), 161–175. https://doi.org/10.1111/bjh.15647
9. Lelonek, E., Matusiak, Ł., Wróbel, T., & Szepietowski, J. C. (2018). Aquagenic pruritus in polycythemia vera: Clinical characteristics. Acta Dermato-Venereologica, 98(5), 496–500. https://pubmed.ncbi.nlm.nih.gov/29437189/
10. Marchetti, M., Vannucchi, A. M., Griesshammer, M., et al. (2022). Appropriate management of polycythaemia vera with cytoreductive drug therapy: European LeukemiaNet 2021 recommendations. The Lancet Haematology, 9(4), e301–e311. https://doi.org/10.1016/S2352-3026(22)00046-1
11. Centers for Disease Control and Prevention. (2024, October 24). Signs and symptoms of stroke. https://www.cdc.gov/stroke/signs-symptoms/index.html
12. Centers for Disease Control and Prevention. (2025, April 23). Deep vein thrombosis and pulmonary embolism (CDC Yellow Book). https://www.cdc.gov/yellow-book/hcp/travel-air-sea/deep-vein-thrombosis-and-pulmonary-embolism.html
13. American Heart Association. (2024, December 12). Warning signs of a heart attack. https://www.heart.org/en/health-topics/heart-attack/warning-signs-of-a-heart-attack