Polycythemia vera vs Secondary polycythemia
How to tell Polycythemia vera and Secondary polycythemia apart when a board question makes them look alike.
PV is JAK2-high red cells with low EPO; secondary polycythemia is EPO-high red cells from hypoxia or EPO source.
Side by side
Polycythemia vera is a primary myeloproliferative neoplasm with increased red cell mass, often leukocytosis/thrombocytosis, pruritus after hot showers, splenomegaly, JAK2 mutation, and low EPO.
Secondary polycythemia is EPO-driven erythrocytosis from hypoxia, high altitude, smoking, sleep apnea, cyanotic heart disease, renal disease, or EPO-producing tumors.
JAK2 activation makes erythroid precursors proliferate independent of normal erythropoietin signaling.
Hypoxia or inappropriate EPO production stimulates otherwise normal marrow to increase RBC production.
High hematocrit, low EPO, JAK2 mutation, panmyelosis, and possible thrombocytosis or leukocytosis support polycythemia vera.
High EPO, hypoxemia or renal tumor clues, and absence of JAK2 support secondary polycythemia.
The trap
Both raise hemoglobin and hematocrit, so EPO level and JAK2 testing are the fastest separator.
Watch it explained
The repair move
For erythrocytosis, pair red cell mass with EPO level before naming primary or secondary disease.
Try a free question
CoreA patient has headaches, facial plethora, splenomegaly, pruritus after hot showers, high hematocrit, leukocytosis, thrombocytosis, JAK2 mutation, and low EPO. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Polycythemia vera. JAK2-positive erythrocytosis with low EPO and panmyelosis points to polycythemia vera.
Why the other choices are tempting
- B. Secondary polycythemia usually has high EPO from hypoxia or EPO-producing disease.
- C. Relative polycythemia is plasma volume contraction rather than increased red cell mass.
- D. Essential thrombocythemia is platelet-predominant.
- E. CML is BCR-ABL granulocytic proliferation.
Flashcards
Tap a card to flip it.
What EPO pattern supports polycythemia vera?
Low EPO supports polycythemia vera.
What mutation supports polycythemia vera?
JAK2 mutation supports polycythemia vera.
Quick answers
What is the fastest way to tell Polycythemia vera from Secondary polycythemia?
PV is JAK2-high red cells with low EPO; secondary polycythemia is EPO-high red cells from hypoxia or EPO source.
What is the key clue for Polycythemia vera?
Polycythemia vera is a primary myeloproliferative neoplasm with increased red cell mass, often leukocytosis/thrombocytosis, pruritus after hot showers, splenomegaly, JAK2 mutation, and low EPO.
What is the key clue for Secondary polycythemia?
Secondary polycythemia is EPO-driven erythrocytosis from hypoxia, high altitude, smoking, sleep apnea, cyanotic heart disease, renal disease, or EPO-producing tumors.
What is the common trap with Polycythemia vera vs Secondary polycythemia?
Both raise hemoglobin and hematocrit, so EPO level and JAK2 testing are the fastest separator.