Secondary Erythrocytosis (Secondary Polycythemia) By Jane Liesveld, MD, James P Wilmot Cancer Institute, University of Rochester Medical Center Reviewed / Revised Jul 2022 | Modified Sep 2022 View Patient Education Secondary erythrocytosis is erythrocytosis that develops secondary to disorders that cause tissue hypoxia, inappropriately increased erythropoietin production, or increased sensitivity to erythropoietin.