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Home Your Health Multimedia Encyclopedia Paroxysmal nocturnal hemoglobinuria (PNH)

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, incidence, and risk factors

Persons 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 lead to aplastic anemia, myelodysplastic syndrome, or acute myelogenous leukemia.

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

Symptoms

• Abdominal pain
• Back pain
• Blood clots -- may form in some people
• Dark urine -- comes and goes
• Easy bruising or bleeding
• Headache
• Shortness of breath

Signs and tests

Red and white blood cell counts and platelet counts may be low.

Red or brown urine signals the breakdown of red blood cells and that hemoglobin is being released into the body's circulation and eventually into the urine.

Tests that may be done to diagnose this condition may include:

• Complete blood count (CBC)
• Coombs' test
• Flow cytometry to measure certain proteins
• Ham's (acid hemolysin) test
• Serum hemoglobin and haptoglobin
• Sucrose hemolysis test
• Urinalysis
• Urine hemosiderin

Treatment

Steroids or other drugs that suppress the immune system may help slow the break down of red blood cells. Blood transfusions may be needed. Supplemental iron and folic acid are provided. Blood thinners may also be needed to prevent clot formation.

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 patients with PNH should receive vaccinations against certain types of bacteria to prevent infection. Ask your doctor which ones are right for you.

Support Groups

Expectations (prognosis)

The outcome varies. Most people survive greater 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.

Complications

• Acute myelogenous leukemia
• Aplastic anemia
• Blood clots
• Death
• Hemolytic anemia
• Iron deficiency anemia
• Myelodysplasia

Calling your health care provider

Call your health care 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

US Food and Drug Administration. FDA Approves First-of-its-Kind Drug to Treat Rare Blood Disorder. Rockville, MD: National Press Office; March 16, 2007. Release P07-47.

Schwartz RS. Autoimmune and intravascular hemolytic anemias. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 164.