Dr. Priyanka Sachdev, MD, explains paroxysmal nocturnal hemoglobinuria (PNH), a rare acquired disorder that causes hemolytic anemia due to a defect in red blood cell membranes. This defect leads to the absence of protective proteins (CD55 and CD59), causing red blood cells, white blood cells, and platelets to be vulnerable to complement-mediated destruction, especially at night due to acidosis. The video covers key clinical features, including the typical triad of hemolysis, pancytopenia, and thrombosis, as well as the tests used for diagnosing PNH.