A 55-year-old man is found to have polycythaemia vera. JAK2 V617F mutation is confirmed. Haematocrit is 56%, and he has no prior thrombosis. He is 55 years old (high-risk based on age). What is the CORRECT target haematocrit and preferred cytoreductive agent?
- A Target haematocrit < 50% with interferon-alpha
- B Target haematocrit < 45% with hydroxyurea as first-line cytoreduction ✓
- C Target haematocrit < 45% with ruxolitinib as first-line
- D Phlebotomy alone without cytoreduction
Correct answer: B. Target haematocrit < 45% with hydroxyurea as first-line cytoreduction
Explanation
The CYTO-PV trial demonstrated that maintaining haematocrit <45% significantly reduced thrombotic events compared to a target of 45-50% in PV. For high-risk PV (age ≥60 or prior thrombosis), cytoreductive therapy with hydroxyurea (first-line) plus phlebotomy is standard. Ruxolitinib (JAK1/2 inhibitor) is second-line for hydroxyurea-intolerant/refractory patients. Interferon-alpha is an alternative, especially in younger patients or pregnant women, but is not universally first-line.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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