Paroxysmal nocturnal hemoglobinuria [Marchiafava-Micheli]

This code represents a rare, acquired, life-threatening disorder characterized by complement-mediated hemolysis, bone marrow failure, and thrombosis. It results from a somatic mutation in the PIGA gene, leading to a deficiency of glycosylphosphatidylinositol (GPI)-anchored proteins on the surface of hematopoietic stem cells.

Use this code for patients definitively diagnosed with paroxysmal nocturnal hemoglobinuria, typically confirmed by flow cytometry demonstrating a deficiency of GPI-anchored proteins (e.g., CD55, CD59) on red blood cells, neutrophils, or monocytes. This diagnosis is often suspected in cases of unexplained hemolytic anemia, pancytopenia, or thrombotic events in unusual locations.

• Do not code with R82.3 (Hemoglobinuria, unspecified) as this is an Excludes1 note, indicating these conditions are mutually exclusive.
• Ensure documentation specifies "paroxysmal nocturnal hemoglobinuria" and not just general hemoglobinuria.
• Consider sequencing this code as a primary diagnosis when it is the reason for the encounter, or as a secondary diagnosis when managing complications related to PNH.