Paroxysmal nocturnal hemoglobinuria (PNH) may cause unpredictable episodes of acute red blood cell destruction (hemolysis). This occurs when a part of your immune system called complement attacks red blood cells that lack certain protective proteins.
At Seattle Cancer Care Alliance (SCCA), our team of experts provides comprehensive diagnostic services, including flow cytometry, bone marrow evaluation, and other special testing, as well as treatment options, such as eculizumab (Soliris), a monoclonal antibody therapy, for people with PNH.
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What is paroxysmal nocturnal hemoglobinuria?
PNH is a rare, acquired blood disease that affects just one to two people per million. It’s caused by an acquired genetic mutation in a subset of the hematopoietic (blood-forming) stem cells. Hematopoietic stem cells are found mainly in the bone marrow. In PHN, the stem cells affected by the mutation and the blood cells they produce (red blood cells, white blood cells, and platelets) gradually become the dominant cells in your marrow.
PNH is a complex disease characterized by hemolytic crises — periods in which large numbers of red blood cells are destroyed. Red blood cells are essential for carrying oxygen from the lungs to the rest of the body. Stem cells with the PNH mutation can also lead to ineffective production of white blood cells, which fight infection, and platelets, which help the blood to clot.
Sometimes, PNH arises after healthy hematopoietic stem cells have been damaged, such as by exposure to toxins, radiation, or chemotherapy, or after the bone marrow has been suppressed by a virus or by a person’s own immune system. These insults to the bone marrow can cause aplastic anemia, and PNH can arise as an outgrowth of recovery from aplastic anemia. In fact, up to 30 percent of newly diagnosed cases of PNH develop from aplastic anemia.
Alternatively, PNH can arise spontaneously without prior marrow damage. In this case, excessive and unexpected breakdown of red blood cells may be the only sign of the disorder, with otherwise normal blood counts.
PNH is most common in adults age 35 to 40, but occasionally it affects children and adolescents or older adults.
Symptoms and diagnosis of paroxysmal nocturnal hemoglobinuria
Hemolysis in PNH can cause acute, severe anemia associated with severe abdominal spasms, headaches, back pain, weakness, occasionally blood clots in unusual places in the body, and extreme fatigue. However, some people with PNH experience no discomfort.
The classic symptom of bloody red or brown urine (hemoglobinuria) actually happens in less than half of those diagnosed with PNH. People with this symptom tend to describe their urine as tea or cola colored. Their urine is usually darker in the morning, because it became concentrated in the bladder overnight, and clearer during the day. The discoloration happens because damaged red blood cells leak the protein hemoglobin into the bloodstream, and this ends up in the urine.
SCCA offers a full array of services to diagnose PNH and related problems that may affect the bone marrow or blood cells.
If your doctor suspects you have PNH, he or she may order a variety of blood tests. Flow cytometry, a very sensitive blood test, has become the standard for detecting PNH. Results from flow cytometry are usually not affected by recent blood transfusions or other factors that can alter results of some other types of tests. In addition to flow cytometry, bone marrow biopsy (examining a small sample of marrow taken with a hollow needle) is important to understand the full nature of PNH and possible associated diseases, such as aplastic anemia or MDS.
Paroxysmal nocturnal hemoglobinuria treatment
SCCA’s team of doctors provides a comprehensive range of treatment options for PNH. Treatment depends largely on the severity of symptoms.
Supplements and medicines
Some people with PNH experience no discomfort and require no treatment beyond folic acid or iron supplements to increase their red blood cell production.
For those requiring more support, doctors may prescribe:
- Prednisone to slow red blood cell destruction
- Anticoagulation drugs to help prevent or treat complications from blood clots
- Eculizumab to help lessen the severity of hemolysis in the bloodstream, reduce the symptoms of PNH, and lower the risk of complications from blood clots
Bone marrow transplant
If you develop bone marrow failure or MDS, your doctor may recommend considering a bone marrow transplant (also called a stem cell or hematopoietic cell transplant). This procedure replaces your blood-forming stem cells with the cells of a donor. Few people with PNH need a transplant, but it is the only cure.