Pure Red Cell Aplasia (PRCA)
What is pure red cell aplasia (PRCA)?
Pure red cell aplasia (PRCA) is a rare disorder of blood production in which the bone marrow, the spongy tissue in the center of the bones, fails to function in an adequate manner resulting in anemia. Red blood cells are responsible for carrying oxygen to the entire body.
The anemia can be either acquired, genetic (inherited) or induced by drugs. In many cases the cause is unknown (idiopathic). The disorder equally affects males and females.
The very rare genetic form, Diamond-Blackfan anemia, is usually diagnosed before the age of 1. About 25 percent of patients with Diamond-Blackfan anemia will have abnormal features in the face, head and hands. Children who are affected tend to be short for their age and puberty may be delayed.
Symptoms and Causes
What are the symptoms of acquired red cell aplasia (PRCA)?
The signs are typical of those in patients with anemia:
What causes acquired pure red cell aplasia (PRCA)?
Acquired PRCA is an uncommon autoimmune disorder that can have multiple causes. These may include:
- A parvovirus B19 infection, which may be toxic to the red blood cells starters (or precursors)
- Certain lymphocytic leukemias (blood cancers) such as large granular lymphocytic leukemia (LGLL)
- Thymoma (a tumor of the thymus, which is a lymphoid organ)
- Autoimmune diseases such as rheumatoid arthritis or lupus
- Common variable immunodeficiency (CVID)
In the case of drug-induced red cell aplasia, antibodies can occasionally develop to a drug used to treat patients undergoing dialysis. Other drugs may be toxic to the red blood cell precursors.
Diagnosis and Tests
How is pure red cell aplasia (PRCA) diagnosed?
- Hemoglobin, the oxygen-carrying protein in red blood cells
- Hematocrit, which is the volume of red blood cells and platelets in blood
- Quantity (and size) of red blood cells
- Quantity of white blood cells
- Quantity of platelets (component that enables clotting)
Low levels of any of these blood components may signal anemia.
- A reticulocyte count, a measure of young red blood cells, may show that your bone marrow is not producing enough red blood cells.
- Your physician may look for evidence of a parvovirus B19 infection by measuring the DNA of the virus in your blood.
- A computed tomography (CT) scan of the chest may be done to look for a thymoma.
- A lymphocyte count in the blood will show whether or not you have a lymphocyte leukemia that may be causing pure red cell aplasia.
- Measuring the monoclonal proteins in the blood checks the adequacy of the immunosystem.
- A bone marrow aspiration (removing a small amount of the liquid portion of bone marrow through a needle) can confirm the diagnosis if the number of red cell precursors in these samples is too low. A bone marrow biopsy can also test iron overload, which can be a complication in patients who need transfusions.
Management and Treatment
How is pure red cell aplasia (PRCA) treated?
Treatment options for PRCA include:
Corticosteroids: Corticosteroid treatment in the form of oral prednisone is considered the mainstay of therapy for pure red cell aplasia.
A corticosteroid helps the bone marrow make more red blood cells. If a corticosteroid will be successful in treating the disease, it will be apparent during the first two to four weeks of treatment (the number of red blood cells will increase over this time).
Side effects of corticosteroid use are more likely if high doses are needed. Some side effects are more serious than others. Common side effects of systemic steroids include:
- Increased appetite, weight gain
- Sudden mood swings
- Muscle weakness
- Vision problems
- Worsening of diabetes
- High blood pressure
- Stomach irritation
- Nervousness, restlessness
- Difficulty sleeping
Immunosuppressive therapy: If the origin of red cell aplasia is an immune system disease, then immunosuppressive drugs may be tried. These include cyclosporine, cyclophosphamide, 6-mercaptopurine, azathioprine and antithymocyte globulin. Treatment with immunosuppressive agents requires a brief hospitalization, and repeat courses may be necessary.
Immunoglobulins: If a persistent parvovirus is found, slow infusions of immune globulins into a vein every three or four weeks may be given. These drugs may cause headache, dizziness, flushing, muscle cramps and joint pain among other side effects, as well as reactions at the injection site (pain, swelling, redness). In some cases, kidney problems may occur.
Blood transfusion: If the anemia is very severe and does not respond to other treatments, or if their side effects are intolerable, blood transfusions may be tried. Typically, these are scheduled every four to six weeks.
Blood transfusions may cause allergic side effects or a problem known as a delayed transfusion reaction in which donated blood cells rapidly break down.
Other adverse events from blood transfusions include infections, the development of red blood cell antibodies (if the red blood cells received do not match the recipient’s own cells) and iron overload (excess iron from blood transfusions may be stored in organs, eventually causing damage to them).
Chelation therapy (treatment of iron overload): Iron overload can be detected by a blood test. The presence of iron in the heart can be detected through the use of magnetic resonance imaging scans. A liver biopsy (removal of a small amount of liver tissue) can identify damage to the liver from iron overload.
Chelation therapy is the removal of iron from the body in the case of iron overload from chronic blood transfusions. The drug deferoxamine is given as an injection over eight to 12 hours, five to seven nights per week. An orange to red tint in the urine is a sign that the drug is working properly; this tint diminishes over time. Reactions at the injection site are a common side effect of chelation therapy.
Removal of the thymus: If a tumor of the thymus is found, its removal may help treatment of acquired pure red cell aplasia.