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What is PNH?

PNH is a serious disease. It destroys an important part of your blood—the red blood cells — and can be life-threatening. Living with PNH can be scary, and the facts about it can be scary too.

  • 35% of patients with PNH die within 5 years of being diagnosed
  • PNH can be devastating, causing organ damage, pain, and impairing your Health-Related quality of life
  • The fact that red blood cells are destroyed in PNH is bad because red blood cells have the important task of helping to deliver oxygen and remove waste from your body

PNH is an acquired disease, which means it develops in some people over time. In PNH, a change occurs in the stem cells in the body, including in the bone marrow, where red blood cells are produced. The stem cell change causes the lifelong production of “bad” cells—cells that are missing important protective proteins. Without these proteins, your body’s natural defense system destroys PNH red blood cells. This destruction is known as hemolysis .


Hemolysis happens constantly and at high rates in PNH, which could put you at risk for serious health problems. Hemolysis is the main cause of the major health problems in PNH, including the most severe. Reducing hemolysis is key to managing your PNH. In addition, the signs and symptoms of PNH are often similar to other diseases. This is what makes PNH tough to diagnose.

The earlier PNH is diagnosed, however, the sooner your doctor can begin to manage your disease.


  • PNH is a serious, unpredictable, and life-threatening disease
  • PNH is progressive . This means your disease can worsen over time, increasing your risk of major PNH-related health problems
  • Everyone experiences PNH differently, making it difficult to diagnose
  • PNH can be managed. There’s a lot you can do

PNH is a rare disease, but you are not alone

  • It affects about 8000 to 10,000 people in North America and Western Europe
  • Both men and women can get PNH
  • PNH occurs across all races
  • PNH can occur at any age; the average age at diagnosis is in the early 30s11

Understanding the disease is the first step toward changing the way you see PNH.

To get more insight into the disease and connect with the PNH community, watch patients share their stories, attend PNH events in your area, or talk to someone who can help you manage your PNH.

Click on a word that is underlined with a light dotted line and an explanation of that word will appear.

Discover how Batina, a real PNH patient, first learned about her disease.

Learn about common complications patients with PNH may experience from Dr. Charles M. Farber, a doctor and scientist of blood and blood diseases.

Watch Scott, a PNH patient, talk about being proactive with his disease.

References: 1. Brodsky RA. Blood Rev. 2008;22:65-74. 2. Hillmen P, Lewis SM, Bessler M, et al. N Engl J Med. 1995;333:1253-1258. 3. Rother RP, Bell L, Hillmen P, et al. JAMA. 2005;293:1653-1662. 4. Rother RP, Rollins SA, Mojcik CF, et al. Nat Biotechnol. 2007;25:1256-1264. [Published correction appears in Nat Biotechnol. 2007;25:1488]. 5. Brodsky RA. Paroxysmal nocturnal hemoglobinuria. In: Hoffman R, Benz EJ Jr, Shattil SJ, et al, eds. Hematology: Basic Principles and Practice. 4th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2005:419-427. 6. Rachidi S, Musallam KM, Taher AT. Eur J Intern Med. 2010;21:260-267. 7. Rosse WF. Paroxysmal nocturnal hemoglobinuria. In: Hoffman R, Benz EJ Jr, Shattil SJ, et al, eds. Hematology: Basic Principles and Practice. 3rd ed. New York, NY: Churchill Livingstone; 2000:331-342. 8. Parker C, Omine M, Richards S, et al; for International PNH Interest Group. Blood. 2005;106:3699-3709. 9. Borowitz MJ, Craig FE, DiGiuseppe JA, et al; for Clinical Cytometry Society. Cytometry Part B. 2010;78B:211-230. 10. Richards SJ, Barnett D. Clin Lab Med. 2007;27:577-590. 11. Socié G, Mary J-Y, de Gramont A, et al; for the French Society of Haematology. Lancet. 1996;348:573-577.