Paroxysmal nocturnal hemoglobinuria (PNH)

  • Definition
    • Paroxysmal nocturnal hemoglobinuria is a rare disease in which red blood cells break down earlier than normal.

  • Alternative Names
    • PNH

  • Causes
    • People with this disease have blood cells that are missing a gene called PIG-A. This gene allows a substance called glycosyl-phosphatidylinositol (GPI) to help certain proteins stick to cells.

      Without PIG-A, important proteins cannot connect to the cell surface and protect the cell from substances in the blood called complement. As a result, red blood cells break down too early. The red cells leak hemoglobin into the blood, which can pass into the urine. This can happen at any time, but is more likely to occur during the night or early morning.

      The disease can affect people of any age. It may be associated with aplastic anemia, myelodysplastic syndrome, or acute myelogenous leukemia.

      Risk factors, except for prior aplastic anemia, are not known.

  • Symptoms
  • Exams and Tests
  • Treatment
    • Steroids or other drugs that suppress the immune system may help slow the breakdown of red blood cells. Blood transfusions may be needed. Supplemental iron and folic acid are provided. Blood thinners may also be needed to prevent clots from forming.

      Soliris (eculizumab) is a drug used to treat PNH. It blocks the breakdown of red blood cells.

      Bone marrow transplantation can cure this disease.

      All people with PNH should receive vaccinations against certain types of bacteria to prevent infection. Ask your health care provider which ones are right for you.

  • Outlook (Prognosis)
    • The outcome varies. Most people survive for more than 10 years after their diagnosis. Death can result from complications such as blood clot formation (thrombosis) or bleeding.

      In rare cases, the abnormal cells may decrease over time.

  • Possible Complications
    • Complications may include:

      • Acute myelogenous leukemia
      • Aplastic anemia
      • Blood clots
      • Death
      • Hemolytic anemia
      • Iron deficiency anemia
      • Myelodysplasia
  • When to Contact a Medical Professional
    • Call your provider if you find blood in your urine, if symptoms worsen or do not improve with treatment, or if new symptoms develop.

  • Prevention
    • There is no known way to prevent this disorder.

  • References
    • Brodsky RA. Proxymal nocturnal hemoglobinuria. In: Hoffman R, Benz EJ Jr., Silberstein LE, Heslop HE, Weitz JI, Anastasi J, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2013:chap 29.

      Michel M. Autoimmune and intravascular hemolytic anemias. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 160.

      Schafer AI. Thrombotic disorders. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 176.