Paroxysmal Nocturnal Hemoglobinuria (PNH) By Evan M Braunstein, MD, PhD, Johns Hopkins University School of Medicine Reviewed / Revised Jun 2022 | Modified Sep 2022 View Patient Education Etiology Pathophysiology Symptoms and Signs Diagnosis Treatment Key Points Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired disorder characterized by intravascular hemolysis and hemoglobinuria.