Dissecting Primary Erythrocytosis Among Polycythemia Patients Referred to an Indian Armed Forces Hospital.

Referrals for evaluation of polycythemia cases have increased since the hemoglobin (Hb) thresholds for diagnosis of Polycythemia Vera (PV) have been lowered by WHO. The current study enrolled patients of age > 18 years from the Indian Armed Forces or their family members with polycythemia from November 2016 to October 2018. After exclusion of secondary causes, 49 patients were diagnosed as Primary Erythrocytosis (PE). The patients were classified into two groups: PV and Idiopathic Erythrocytosis (IE) and a systematic comparison of clinical and laboratory features of the two groups was done. The prevalence of PV in PE was 20.4% (10 of 49) while the rest 39 (79.6%) had IE. Seven PV patients had JAK2 V617F mutation, one had JAK2 Exon12 mutation, and two were JAK2 negative PV. Nine of 10 (90%) PV patients had Hb > 18.5 g/dl, while only 21 of 39 (53.8%) IE patients had Hb > 18.5 g/dl (p = 0.06). None of the JAK2 mutated patients had Hb < 18.5 g/dl. We conclude that PV is more prevalent in patients of PE with Hb > 18.5 g/dl. Most patients with Hb between 16.5-18.5 g/dl would still be classified as IE. We advocate the need for further studies evaluating the utility of investigating all patients of PE with the revised WHO Hb threshold as well as studies on genetic profile of IE patients from India. © Indian Society of Hematology and Blood Transfusion 2019.