Effect of Altitude on Polycythemia Vera: Is it Necessary to Change Limits?

Serin, Istemi, Ahmet Unal, Arzu Dobral, Fatma Elif Eroglu, Erdem Ayik, Jale Oz Unal, Mehmet Barış Cengiz, Okan Kati, Toros Taskin, Vural Bastug, and Abdulkadir Karismaz. The effect of altitude on polycythemia vera: Is it necessary to change limits? High Alt Med Biol. 00:00-00, 2025. Background: Polycythemia vera (PV) is a myeloproliferative disease characterized by high hemoglobin/hematocrit levels accompanied by JAK2 mutations. In this study, we aimed to establish a new hemoglobin cut-off value for the diagnosis and further evaluation of PV, taking into account the altitude of the regions where patients reside. In addition, we sought to examine the impact of altitude on patients diagnosed with PV and secondary polycythemia (SP) within our case series. Methods: Patients living in Istanbul and Agri who were evaluated for PV at the hematology outpatient clinic of Istanbul and Agri Training and Research Hospitals between January 20, 2023, and January 20, 2024, were included in the study. The average altitude of the center of Agri is 1,630 m, while the center of Istanbul is 30 m. Results: The mean altitude of residence for individuals diagnosed with PV was 326 ± 259 m, whereas it was significantly higher at 1,065 ± 675 m in the SP subgroup (p < 0.001). However, in subgroup analyses of patients with PV and SP, altitude was not a significant factor influencing hemoglobin levels. Conclusions: Our study results did not support the use of different hemoglobin cut-off values or correction factors for further evaluation of PV in patients living at different altitudes. Our results might not be applicable to altitudes higher than those we examined.