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Seema Dawood: What is Polycythemia Vera?
Apr 7, 2026, 17:21

Seema Dawood: What is Polycythemia Vera?

Seema Dawood, Medical Laboratory Technologist at The Aga Khan University Hospital, shared a post on Linkedin:

“Polycythemia Vera (PV)

Type of Myeloproliferative Neoplasm (MPN) characterized by an abnormal increase in red blood cell production in the bone marrow.

It is primarily caused by a JAK2 mutation (most commonly V617F), which makes hematopoietic cells overly sensitive to erythropoietin (EPO), leading to increased RBC production even when EPO levels are low.

Pathophysiology

  • JAK2 V617F mutation is present in approximately 95% of cases.
  • Another 2–3% carry JAK2 exon 12 mutations.
  • The bone marrow becomes hypercellular with trilineage proliferation, involving erythroid, granulocytic, and megakaryocytic lineages.
  • This results in elevated RBCs, WBCs, and platelets, a condition known as ‘Panmyelosis.’

Laboratory Findings

  • Elevated Hb and Hct (Hct > 49% in men, > 48% in women)
  • Increased RBC mass
  • Low serum EPO (an important diagnostic clue)
  • WBC and platelet counts may also be increased
  • Bone Marrow

Hypercellular marrow

Trilineage growth: erythroid, granulocytic, and megakaryocytic proliferation

  • Megakaryocytes are pleomorphic and often form clusters
  • Genetics

Presence of JAK2 V617F or JAK2 exon 12 mutation

WHO Diagnostic Criteria (2022)

Diagnosis requires all 3 major criteria, or 2 major plus 1 minor.

  • Major Criteria

Elevated Hb, Hct, or increased RBC mass

Bone marrow showing hypercellularity with Panmyelosis

JAK2 mutation (V617F or exon 12)

  • Minor Criterion

Low serum EPO

  • Complications
  • Thrombosis
  • Hemorrhage
  • Splenomegaly

Disease progression to:

  • Myelofibrosis (post-PV MF)
  • Acute Myeloid Leukemia (AML) (less than 5%).”

Seema Dawood

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