Inform your doctor if you are on any medications, have any allergies or underlying medical conditions before your Paroxysomal Nocturnal Hemoglobinuria (Pnh) (Cd55 59) Flow Cytometry Blood. Your doctor will give specific instructions depending on your condition on how to prepare for Paroxysomal Nocturnal Hemoglobinuria (Pnh) (Cd55 59) Flow Cytometry Blood.