PNH Facts

PNH Facts

Paroxysmal Nocturnal Hemoglobinuria (PNH) is a rare, acquired, progressive and life-threatening blood disease. Red blood cells in a person with PNH are attacked by the immune system because they lack a special protein. The destruction of red blood cells is called hemolysis, and the contents of the destroyed red blood cells get into the blood stream Additional complications include thrombosis and bone marrow failure.

PNH affects one to two people per million and is diagnosed most often between 35 to 40 years of age. Occasionally children and adolescents may be diagnosed. About 30 percent of those diagnosed have had Aplastic anemia as well.


PNH is a complex disease that has many symptoms that are similar to other diseases, which makes it difficult to diagnose accurately. However, particular patients will experience symptoms unique to them and may include severe abdominal pain or headaches, back pain, weakness, and recurrent infections. Anemia, thrombosis (clotting), extreme fatigue, and poor physical function are also symptomatic of PNH. The classic symptom of bloody urine (hemoglobinuria) is seen in less than half of patients with PNH. Described as “tea-colored,” patients usually find their urine to be darker in the morning hours and clearer throughout the day.

Attacks of hemoglobinuria are thought to be brought on by stress, infections, exercise, or alcohol.

Blood clots are the leading cause of death in PNH patients. 


Flow cytometry is a very sensitive test that has become the standard test for detecting PNH. Other lab tests may also be used, but may turn up false negative results.


Doctors do not yet fully understand what causes PNH. However, PNH patients are less able to produce blood cells and they have abnormal red blood cells that may be destroyed by their immune system.

PNH affects men and women of all races, backgrounds, and ages. Most often, it develops in people between the age of 20 and 40 years. Sometimes people with PNH have other blood disorders such as aplastic anemia