Christopher Patriquin, MD, Hematologist at Toronto General Hospital, discusses the challenges of diagnosing paroxysmal nocturnal hemoglobinuria (PNH) due to its varied symptoms, such as thrombosis, anemia, and unusual pain in the abdomen or chest. Diagnosis can take time as these symptoms overlap with other conditions. Once suspected, PNH is confirmed through a flow cytometry test, which has high sensitivity. The key challenge is recognizing the condition to initiate proper testing and treatment, as untreated PNH can lead to serious complications like kidney failure or difficulty breathing.