Paroxysmal nocturnal hemoglobinuria (PNH)

Paroxysmal nocturnal hemoglobinuria (PNH)

Definition:

A rare, acquired disorder of red blood cells in which an abnormal cell surface molecule leads to premature destruction (hemolysis) of the cells. This destruction is intermittent (paroxysmal).

Alternative Names:

PNH

Causes, incidence, and risk factors:

The exact cause is unknown. It is thought to be a disorder of the stem cell (the precursor of blood cells) in which a sensitivity to complement (a substance produced by the immune system) occurs in the cell membrane. The disease can affect people of any age. Red blood cell, white blood cell and platelet counts may be low. Urine may be intermittently red or brown, signifying the breakdown of red blood cells with release of hemoglobin into the circulation and then the urine. Blood clots may form in some people. The disease may arise in relation to aplastic anemia, and may progress to acute myelogenous leukemia. Risk factors, except for prior aplastic anemia, are not known.

Symptoms:

intermittent dark urine
abdominal pain
back pain
headache
shortness of breath
easy bruising or bleeding in the skin

Signs and tests:

CBC may show low white blood cell count, red blood cell count, and platelets.
sucrose hemolysis test is positive.
Ham's (acid hemolysin) test is positive.
urinalysis shows hemosiderin and hemoglobin.

This disease may also alter the results of the following tests:

hemoglobin; serum

Treatment:

Steroids may be effective in suppressing hemolysis. Blood transfusions may be required. Anticoagulation therapy may also be required to prevent clot formation. Antithymocyte globulin (ATG), a therapy derived from horse serum, may help restore normal blood cell production. Bone marrow transplantation, when successful, can cure this disease.

Expectations (prognosis):

The outcome is variable, with most people surviving approximately 10 years following diagnosis. In rare cases, the abnormal cells may decrease over time. Death can be caused by complications of blood clot formation (thrombosis).

Complications:

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.

Review Date: 10/10/2001
Reviewed By: Rebecca Elstrom, M.D., Division of Hematology-Oncology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

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