Idiopathic Erythrocytosis: Vascular Complications

Abstract Idiopathic Erythrocytosis (IE) is a diagnosis of exclusion once primary and secondary causes have been eliminated; yet IE remains an enigmatic disorder. Published series from decades ago (Modan & Modan J. Hematol [1968] 14:375; Pearson & Wetherly-Mein, Clin.Lab Hematol. [1974] 1:189) have reported high rates of vascular complications (46%) and advise phlebotomy to keep the hematocrit to less than 45%. A More recent series (McMullin B.J. Hematol. [2005] 130:174) advise no need for phlebotomy in patients with no co-morbidities such as vascular disease, diabetes, or hypertension. In an attempt to determine some practice guidelines, we undertook a retrospective analysis of patients identified with IE within our practice and to quantify the rates of vascular complications, if any. From January 1, 2016 to December 31. 2020 99 patients were referred because of erythrocytosis. Twenty of these 99 patients had polycythemia rubra vera and 77 had secondary erythrocytosis ( 64 males, 13 females, median age 61 years). Of these 77 patients with secondary erythrocytosis, 40 had obstructive sleep apnea, 10 men abused testosterone, and 1 patient each was either post splenectomy or post kidney transplant, 1 patient had a renal cell carcinoma, and 1 patient had familial erythrocytosis. Twenty patients were identified as having IE and all 20 did not have a JAK2 mutation. There 13 males and 7 females with a median age of 63 years (range 31-76). The median hemoglobin was 17.2 gm/dl and the median hematocrit was 51.2 (range 15.0 to 18.4 and 49% to 55% respectively). The median erythropoietin level was 9.9 mu/ml (range 5-38.5). Two of the 20 patients underwent therapeutic phlebotomy and developed no vascular complications. Eighteen patients were simply followed with phlebotomy despite having comorbidities of hypertension, increased BMI, type II diabetes, and none developed vascular complications. IE remain an enigmatic disorder that requires uniform diagnostic criteria as well as uniform practice guidelines; however, given our retrospective review, we do not believe that therapeutic phlebotomy is justified. Disclosures No relevant conflicts of interest to declare.