Paroxysmal Nocturnal Hemoglobinuria (PNH)
CD55/CD59 proteins also known as decay accelerating factors found on surface of RBCs protect them from complement-mediated hemolysis. PNH is a deficiency in glycosylphosphatidylinositol-anchor molecules that decay factor attachment or binding to RBCs, resulting in complement mediated hemolysis and thrombosis. How does patients present? PNH can manifest as iron deficiency anemia, episodic dark urine, venous thrombosis (most commonly mesentric and hepatic vein thrombosis), pancytopenia and abdominal pain. Most accurate diagnostic test is CD55/CD59 absence via flow cytometery. Prednisone is the best initial therapy. Allogenic bone marrow transplant is curative. Eculizumab, a complement inhibitor can be used for hemolysis and thrombosis.