Tehran University of Medical Sciences International Journal of Hematology-Oncology and Stem Cell Research 2008-2207 14 4 2020 10 07 232 236 EN Rafet Eren University of Health Sciences, Okmeydanı Training and Research Hospital, Department of Hematology, Istanbul, Turkey Bahar Sevinçoğlu University of Health Sciences, Okmeydanı Training and Research Hospital, Department of Internal Medicine, Istanbul, Turkey Esra Doğan University of Health Sciences, Okmeydanı Training and Research Hospital, Department of Hematology, Istanbul, Turkey Demet Aydın University of Health Sciences, Okmeydanı Training and Research Hospital, Department of Hematology, Istanbul, Turkey Nihan Nizam İstanbul University, İstanbul Faculty of Medicine, Department of Internal Medicine, Istanbul, Turkey Naciye Demirel University of Health Sciences, Okmeydanı Training and Research Hospital, Department of Hematology, Istanbul, Turkey 2019 10 23 2020 03 03 Background: We evaluated the frequency of subnormal erythropoietin levels, JAK2V617F positivity and polycythemia vera (PV) in patients who did not meet WHO 2008 criterion for hemoglobin levels but were suggested to be investigated for PV in 2016 revision. Materials and Methods: We assessed the data of 92 patients, who were further evaluated with JAK2V617F mutation and serum erythropoietin (EPO) levels and bone marrow biopsy, if necessary. We also compared this patient group with 20 patients whose Hgb>18.5 g/dL for men and >16.5 g/dL for women. Results: Nine patients (45%) in the higher hemoglobin group were JAK2V617F positive, while 4 patients (4.3%) in the lower hemoglobin group were JAK2V617F positive (p<0.001). The number of patients with serum EPO levels <4.3 mIU/mL was significantly higher in the higher hemoglobin group (n=13, 65%) than the lower hemoglobin group (n=7, 7.6%) (p<0.001). Finally, the number of patients who received a diagnosis of PV was significantly higher in the higher hemoglobin group (n=13, 65%) than the lower hemoglobin group (n=9, 9.8%) (p<0.001). Conclusion: We found a substantial increase in patients who were candidates for testing for PV with the introduction of WHO 2016 criteria; these patients were diagnosed with PV with a rate (9.8%) that cannot be underestimated. https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/view/1198 https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/download/1198/864