Idiopathic thrombocytopenic purpura (ITP) is a not infrequent autoimmune bleeding disorder characterized by the abnormally low levels of blood cells called platelets, creating a condition known as thrombocytopenia. Platelets are specialized blood cells that help prevent and stop bleeding by inducing clotting. In many ITP cases, there are no readily apparent causes or underlying disease (idiopathic), but frequently there are associated collagen vascular diseases or underlying neoplasms, most frequently lymphoid. The cells of the immune system, lymphocytes, produce anti-platelet antibodies that attach to the platelets. The presence of antibodies on platelets leads to their destruction in the spleen. The disorder is characterized by abnormal bleeding into the skin resulting in bruising, which is what the term purpura means. Bleeding from mucous membranes also occurs, and may subsequently result in low levels of circulating red blood cells (anemia).
ITP presents as a brief, self-limiting form of the disorder (acute ITP) or a longer-term form (chronic ITP). Acute ITP accounts for about 50% of cases, and chronic ITP accounts for the remainder. Eighty percent (80%) of the children with ITP have the acute form while the chronic form affects mostly adults. The acute form usually resolves without treatment (spontaneously) within three to six months. When thrombocytopenia lasts for more than six to 12 months, ITP is classified as the chronic form. Onset of acute ITP is often rapid, while the onset of the chronic form may be gradual.
A child or adult with idiopathic thrombocytopenic purpura may display no symptoms (asymptomatic). Symptoms of ITP may not appear until the platelet count is extremely low. Such symptoms may include:
– Skin that bruises very easily
– A rash consisting of small red dots (petechiae) that represent small hemorrhages
– Bleeding from any area of the body made obvious by blood in urine or feces
– Bleeding from the gums
– Frequent and long-lasting nose bleeds
– Abnormal menstruation
In some cases, frequent bleeding episodes may result in low levels of circulating red blood cells (anemia), which may produce weakness and fatigue. Additionally, people with this disorder may experience fevers and abnormal enlargement of the spleen (splenomegaly). Some women with ITP may experience prolonged and heavy menstrual bleeding. In rare cases of ITP, a serious condition known as bleeding into the brain (intracranial hemorrhage) may occur.
Idiopathic thrombocytopenic purpura belongs to a group of disorders in which the body’s natural immune defenses inappropriately act against the body’s own tissues (autoimmune disorders). In ITP, an abnormal immune reaction appears to lead to destruction of certain blood cells known as platelets. For reasons that remain as yet unknown, lymph tissues and the spleen are stimulated to produce anti-platelet antibodies that mistakenly attach to platelets, forming an “antibody-platelet complex”. Antibodies are produced by the body’s immune system to react to foreign substances, known as antigens. In many cases, the exact cause of the production of these anti-platelet antibodies is unknown (idiopathic), but in some underling collagen vascular/rheumatologic conditions as well as malignancy may stimulate antibody production
ITP affects normal platelets as they circulate through the spleen. The antibody-platelet complex is recognized as foreign by the immune system, which then goes to work to destroy it. After a while, the platelet count in the blood declines and thrombocytopenia (abnormally low numbers of platelets) ensues.
In children, ITP often occurs following an acute viral infection or upper respiratory illness suggesting that antibodies produced to fight foreign viral substances (antigens) may cross- react with the antigens and, in turn, destroy platelets.
Some cases resembling ITP may result from the use of certain drugs. According to the medical literature, Helicobacter pylori, a bacterium that has been shown to cause stomach ulcers, is associated with the development of ITP in some cases.
The incidence of idiopathic thrombocytopenic purpura among adults annually in the USA has been estimated at 66 cases per million. The annual incidence among children has been estimated at about 50 cases per million of population. Chronic ITP is thought to make up about 10 cases per million per year.
The incidence varies from country to country with studies in Denmark reporting 10-40 cases per million per year. Other studies in Kuwait report 125 cases per million per year.
Among adults diagnosed with chronic ITP, there are 2.6 cases among women for every case involving a male. Among children diagnosed with acute ITP, the male to female ratio is almost equal, with 52% male to 48% female.
Among adults, the incidence is greatest at ages 20 to 50 years. Among children, the incidence is greatest at ages 2 to 4 years. About 40% of all patients diagnosed with one form of ITP are children younger than 10 years of age.
The diagnosis of ITP is usually made by excluding other causes of thrombocytopenia, including certain medications or the presence of disorders such as acute leukemia and aplastic anemia. The disorder is commonly without apparent symptoms (asymptomatic). Low platelet counts may be found after routine blood tests ordered for other purposes.
Blood tests to determine platelet counts and the presence of platelet antibodies are commonly ordered. Normal appearing red blood cells or white blood cells will rule out or exclude leukemia and/or aplastic anemia from the diagnosis. The presence of unusual cells in the blood will call for the use of a needle biopsy of the bone marrow.
In some cases, especially with the acute from of ITP, no therapy may be necessary and the disorder may resolve itself (spontaneous resolution). When therapy is necessary, treatment with corticosteroid drugs (e.g., prednisone) is usually administered, and this is the mainstay of therapy. If platelet levels do not improve after corticosteroid treatment, affected individuals may require ongoing treatment with intravenous immunoglobulins (IVIG), usually through monthly infusions, but this does not lead to a cure.
The orphan drug anti-D (WinRho SDF), a form of gammaglobulin, was approved by the Food and Drug Administration (FDA) for the treatment of individuals with ITP who are RH positive and have not received a splenectomy. The drug may be used repeatedly in affected individuals, particularly children, who have the acute or chronic form of ITP. For information about this drug, contact:
Cangene bioPharma, Inc.
Baltimore, MD 21230
Product Website: www.winrho.com
Anti CD20 antibody, Rituximab (Rituxn) reduces IgG antibody production and is frequently used in patients refractory to other therapies.
Because the spleen plays a role in destroying antibody-covered platelets, surgical removal of the spleen (splenectomy) may be recommended in cases where affected individuals fail to respond to steroids or who fail to maintain a remission when steroids are discontinued. Splenectomy improves platelet counts in approximately 70 percent of cases and can achieve a remission in 50 to 60 percent.
If the patient has antibodies or evidence of Helicobacter pylori infection, antibiotics and proton pump inhibitors may ameliorate the condition. (This is much more common in Asia)
In 2008, the FDA approved Promacta manufactured by GlaxoSmithKline (GSK) for patients with chronic immune thrombocytopenic purpura to increase platelet counts and reduce bleeding. According to GSK, Promacta is the first pill to treat the condition. Other medications are available from different manufactures with the same mechanism of action.
In 2008, the FDA approved romiplostim for subcutaneous injection (Nplate, made by Amgen Inc.) for the treatment of thrombocytopenia in patients with ITP who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. Romiplostim is a thrombopoietin (TPO) receptor agonist that stimulates bone marrow megakaryocytes to produce platelets.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
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