July 12, 2022
Years published: 1986, 1987, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2003, 2004, 2010, 2015, 2019, 2022
NORD gratefully acknowledges the Platelet Disorder Support Association and PDSA Medical Advisors James Bussel, MD and Douglas Cines, MD, for assistance in the preparation of this report.
Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder characterized by abnormally low levels of blood cells called platelets, a situation referred to as thrombocytopenia. Platelets are specialized blood cells that help maintain the integrity of the walls of blood vessels and help prevent and stop bleeding by accelerating clotting where it is needed. A normal platelet count ranges from approximately 150,000 to 400,000 per microliter (µL) of blood depending on the laboratory. However substantial bleeding does not usually occur until the platelet count is less than 50,000 or even 30,000/µl.
If someone has a platelet count lower than 100,000/µL of blood with no other reason for having low platelets, that person might have ITP. Platelet counts of 100-150,000/µL are frequent, have many possible causes and are usually less clinically important. There is currently no definitive laboratory test to diagnose ITP. Measurement of anti-platelet antibody levels is not considered to be diagnostic. Rather ITP is a “diagnosis of exclusion” meaning that other causes have been considered and are either eliminated or are unlikely. Tests to exclude other causes of thrombocytopenia depend on severity, symptoms, personal and family medical history and experience of the treating physician.
As the platelet count falls, the risk of developing bleeding symptoms increases, especially below 50,000/L (if platelet function is relatively normal). ITP can often be discovered incidentally in patients who are asymptomatic (meaning they do not have symptoms of ITP other than a low platelet count). Such incidental cases arise when a blood count is obtained for another reason, such as a routine yearly checkup or before a surgical procedure or during pregnancy. More often, patients with ITP develop symptoms unexpectedly, such as abnormal bleeding into the skin resulting in either bruising (purpura), or tiny red dots on the skin called petechiae. Bleeding from mucous membranes such as the nose and mouth, and less commonly the stomach, gastrointestinal and urinary tracts may also occur and may subsequently result in low levels of circulating red blood cells (anemia) especially in women who are having very heavy periods (menses). Fortunately, internal bleeding is uncommon. The most concerning, but rare, form of this is bleeding in the brain called an intracranial hemorrhage (ICH).
ITP is called “newly diagnosed” when it has been present for less than 3 months, “persistent” when present for 3-12 months, and “chronic” when present for longer than one year. The term “acute” is no longer used.
At least half of all adults with ITP disclose that they experience fatigue and an impaired quality of mental and emotional health, physical health, and social functioning. ITP can impact so many aspects of a patient’s and family’s life that school, work, relationships and sometimes daily living becomes challenging. Symptoms that often interfere with daily activities include anxiety, fear, depression, embarrassment because of unexplained bruising and other bleeding symptoms such as nose bleeds (epistaxis) or oral blood blisters, isolation, social inadequacy and frustration with a patient’s inability to control their body and their health. This list does not include the side effects of treatments which, while possibly improving platelet counts, can exacerbate some of these associated complications, such as the use of corticosteroids, a common first-line treatment. Together, the multi-faceted effects of ITP can take a significant toll on a patient’s and family’s quality of life.
Children have similar types of bleeding symptoms. At diagnosis their platelet counts may be lower than seen in adults, so they may have more skin or oral bleeding but are less likely than older adults to have serious, life-threatening bleeding. Since small children often feel normal when they present, their parents are usually more worried and feel worse than the children do. Adolescents behave more like adults. Children are less able to describe their symptoms but studies using an ITP survey called the Kid’s Tool Kit have demonstrated impaired quality of life. Small children may reflect irritability instead of fatigue.
A child or adult may display no symptoms (be asymptomatic) when a low platelet count is first discovered, or bleeding symptoms may appear first and then the platelet count is discovered to be low. Such symptoms may include:
• Skin that bruises very easily and even spontaneously.
• A rash consisting of small red dots (petechiae) that represent small hemorrhages.
• Bleeding from the gums.
• Frequent nose bleeds that are long-lasting and hard to stop.
• Blood blisters on the inside of cheeks.
• Excessive and/or prolonged menstrual bleeding.
• Less commonly, signs of internal bleeding with blood in urine, vomit or bowel movements.
• In rare cases, serious bleeding into the brain (intracranial hemorrhage). This occurs in < 1% of children and increases in frequency in adults especially over the age of 60. • Bleeding can lead to anemia, which may itself cause fatigue. Impaired quality of life from fatigue, anxiety and side effects of treatment.
The fundamental abnormality in ITP is that the patient’s immune system tags their own platelets as “foreign”, leading their B-lymphocytes and plasma cells to produce self-reactive anti-platelet antibodies that attach to platelet surfaces. A type of white blood cells in the spleen and in other organs, called macrophages, normally recognize antibody-coated particles. In ITP, antibody-coated platelets are ingested and subsequently destroyed within the macrophages. The bone marrow attempts to compensate but is often unable to keep up with the destruction, especially in severe cases. Platelet production may also be impaired when anti-platelet antibodies bind to the cells in the bone marrow called megakaryocytes that produce platelets. However, ITP is heterogeneous with respect to pathophysiology, clinical symptoms such as risk of bleeding and thrombosis or of fatigue, coincident autoimmune disease, and responses to treatments.
Antibodies are normally produced by the body’s immune system in response to foreign substances known as antigens, for example on viruses and bacteria, after vaccination, or on red blood cells or tissue from unrelated people. Autoimmune diseases like ITP belong to a group of disorders in which the body’s natural immune defenses inappropriately act against its own cells or tissues. In ITP, this abnormal immune reaction leads to destruction of the individual’s own platelets. For reasons that are unknown, platelets are recognized as foreign by the immune system, stimulating lymphocytes in the bone marrow, spleen and elsewhere to produce antibodies that attach to platelet surfaces. In most affected individuals, the platelets are the only target of the misdirected immune response and there is no underlying broad autoimmune disease, and this case the disorder is called primary ITP or just ITP. However, in perhaps in 1 in 5 individuals with ITP, it develops in the context of another disorder that predisposes to making autoantibodies to additional targets in addition to platelets. This is called secondary ITP and is discussed below. In most individuals, however, the disorder restricted to platelets and no connection to another disease is evident although the cause of anti-platelet antibody production remains unknown.
The autoantibodies in ITP bind to otherwise normal platelets in the blood that circulates through the spleen, liver and elsewhere. The antibody-platelet complexes are recognized by tissue macrophages, which ingest and destroy antibody-coated platelets as they would normally when then encounter any antibody-coated foreign particle. The bone marrow attempts to compensate by producing more platelets, but the rate of platelet destruction may exceed the marrow capacity to make new platelets and thrombocytopenia develops. Platelet production in the bone marrow may also be impaired when the same autoantibodies that bind to the platelets attach to the platelet precursors called megakaryocytes or when T cells attack them. Therefore, the mechanisms underlying ITP and the resulting very low platelet counts can involve increased platelet destruction, reduced or inadequate platelet production, or both. It is not currently possible to define the relative importance of these two contributing factors in a specific patient.
In children, ITP often appears soon after an otherwise unremarkable viral infection. This suggests that antibodies produced to fight foreign viral substances (antigens) may “cross-react” with similar appearing antigens on platelets, which in turn lead to platelet destruction. This has been shown in the case of chicken pox, for example. However, there isn’t a reliable way to predict which child (or adult) will get better and who will develop chronic ITP. The general pathophysiology of ITP in children is similar to that of adults but children seem to be able to recover spontaneously at a higher rate.
It is quite rare for patients with ITP to have a family history of low platelet counts. When there is a family history of thrombocytopenia, an inherited (genetic) platelet disorder should be considered. Inherited thrombocytopenias are uncommon but are under-diagnosed. In addition to a family history of low platelet counts, the size (usually large) and shape of the platelets on a blood smear, syndromic features and failure to respond to steroids and/or IVIg should all suggest consideration of an inherited platelet disorder. An Inherited thrombocytopenia is not considered a secondary cause of ITP although in certain cases, such as with 22q11.2 deletion syndrome and Wiskott-Aldrich syndrome, secondary ITP can develop in inherited thrombocytopenia. Genetic testing can be used to diagnose many forms of inherited, i.e., familial, platelet disorders but many such cases remain undiagnosed even after such testing.
Secondary ITP can also be caused by certain autoimmune disorders such as lupus, inherited immune disorders such as common variable immunodeficiency (CVID), autoimmune lymphoproliferative syndrome (ALPS), and Evans syndrome, in which antibody-mediated red cell destruction accompanies ITP. Secondary ITP can also be caused by persistent infections (such as HIV, hepatitis B or C, or CMV), in addition to the ulcer-causing stomach bacterium such as Helicobacter pylori (primarily in certain countries, such as Japan and Italy), and lymphoproliferative disorders (such as chronic lymphocytic leukemia) that impair the immune system. A few cases resembling ITP result from the use of certain drugs. Secondary ITP can also occur in children after vaccination for measles-mumps-rubella (MMR) although rare. Recent cases of ITP have also been reported infrequently after both COVID infection and vaccination to prevent it.
ITP occurs in people of all races and ethnicities. ITP can occur at any age from 3 months to over 100 years of age. About 40% of all patients diagnosed with ITP are children younger than 10 years of age. The incidence is highest between 2 to 4 years of age, and males and females are affected equally until adolescence. Between adolescence and the age of 60, ITP is more common in females. The highest prevalence is among males and females over the age of 60.
The incidence (how many people are diagnosed each year) of adult ITP in the USA is roughly estimated to be 3.3 per 100,000/year. The prevalence (how many have ITP at any time) is 9.5 per 100,000. In a study that analyzed data from the Maryland Health Care Commission, the prevalence of ITP was estimated to be 9.5 per 100,000 children ages 1-5, 7.3 per 100,000 in children ages 6-10, and 4.1 per 100,000 in children of ages 11-14. Since children with ITP usually recover, the number of children who have ITP at any one time is almost equal to those diagnosed annually. Worldwide, it is estimated that there are well over 200,000 people affected by ITP.
In 80% of children who present with ITP, the disorder is self-limiting and resolves with or without treatment (i.e., spontaneously) within 12 months, usually sooner. In contrast, the proportion of adults with ITP who have a life-long chronic condition is much higher, approximately 50-70%, although firm data is lacking. One study suggested that 60% of adults diagnosed with ITP will improve within 3 years. ITP that develops in adolescents most often follows the clinical course seen in adults.
Thrombocytopenia can also be due several other disorders that can resemble ITP in addition to inherited and secondary thrombocytopenia. It is important that physicians develop a differential diagnosis for other possible causes of thrombocytopenia, to consider the full spectrum of what could be underlying the thrombocytopenia. The most likely underlying conditions depend on patient age, sex and many other features of the presentation. Clinical judgment is important since it is not possible to do testing for every other cause of thrombocytopenia.
Occasionally patients may have enlarged lymph nodes, a history of recurrent infections or other findings not typical for ITP. Thrombocytopenia can also be caused by many other blood (hematological) disorders that reduce the ability of the bone marrow to produce platelets. One example is called myelodysplasia which in its mildest form must be considered in the differential diagnosis of ITP, especially in the elderly. Myelodysplasia is suspected based on abnormalities in the blood smear and can often be diagnosed with a bone marrow examination. Other causes of bone marrow failure include aplastic anemia, leukemia or rarely folate or B12 deficiency.
Platelets can dwell (pool) in an enlarged spleen (splenomegaly) from any cause or can be destroyed because of an overactive spleen (hypersplenism). Hypersplenism is often caused by liver disease due to viral hepatitis or alcohol. Thrombocytopenia due to splenomegaly or hypersplenism is usually not as severe as in ITP. The diagnosis may be suspected on physical examination or by abdominal imaging.
As mentioned above, immune thrombocytopenia can be secondary to a systemic autoimmune disorder such as systemic lupus erythematosus. Adverse drug reactions (drug-induced thrombocytopenia) are also potential causes of thrombocytopenia. Quinidine, quinine, valproate and heparin are examples drugs associated with the development of immune thrombocytopenia.
Infections can result in thrombocytopenia that may be hard to distinguish from ITP. These infections include HIV, hepatitis B and C, H Pylori and CMV, among others. Thrombocytopenia in these settings may not be immunologically mediated as in ITP. The presence of an infection may be suspected by finding abnormal liver tests and/or atypical lymphocytes on blood smear and then confirmed with specific diagnostic tests.
There are some disorders in which thrombocytopenia is accompanied by thrombosis or vessel injury. Thrombotic thrombocytopenia purpura (TTP) is a rare, but quite serious blood disease. In adults it is found most commonly in young females; the rare cases in children are more common in adolescent females. Major symptoms may include disturbances (interruptions) in blood supply due to clotting that can involve any of several organs including the brain, severe thrombocytopenia and accelerated destruction of red blood cells leading to their characteristic fragmented appearance on the blood film (microangiopathic hemolytic anemia). Thrombotic thrombocytopenia purpura is most often caused by an autoantibody that lowers the level of or blocks the function of an enzyme known as ADAMTS13 that helps to control blood clotting. Treatment includes immediate plasma exchange although caplicizumab, which inhibits von Willebrand factor action, also works very quickly. Steroids are typically administered on day 1 and anti-CD20 is often added to the therapeutic regimen. Another form of TTP is an inherited absence of ADAMTS13 and requires replacement therapy with cryoprecipitate or plasma. ADAMTS13 concentrates are in development. These cases may present when exacerbated by infection. (For more information on this disorder, choose “thrombotic thrombocytopenia purpura” as your search term in the Rare Disease Database).
Hemolytic uremic syndrome (HUS) is another cause of thrombocytopenia, anemia, and thrombosis. The epidemic form occurs in very small children/infants and presents with anemia and thrombocytopenia in the setting of acute renal failure. It is caused by a toxin produced by certain E Coli bacteria. Classically, there is bloody diarrhea which resolves followed several days later by HUS. There are also inherited forms called “atypical HUS” due to genetic abnormalities in the alternative pathway of complement. HUS also occurs in adults, during pregnancy or rarely as a side effect of certain medications.
Heparin-induced thrombocytopenia (HIT) is the most common drug-induced, antibody-mediated thrombocytopenic-thrombotic disorder. Heparin is often used to prevent blood clotting (anticoagulant). HIT generally occurs a week after first exposure to the drug and sooner with subsequent exposures. The antibodies in HIT bind to heparin in combination with a protein released from platelets called PF4. HIT antibodies activate platelets and other cell types, predisposing to formation of blood clots (thrombosis) in veins or arteries. This is a disorder recognized in hospitalized patients but not in outpatients taking low doses of heparin subcutaneously to prevent clot formation. HIT is rare in children.
The antiphospholipid syndrome (APS) is a disorder associated with autoantibodies to various phospholipids that make up the membranes of cells, such as cardiolipin, and to proteins that bind to such phospholipids, such as beta-2-glycoprotein 1. Patients with APS may present with arterial or venous thrombosis in any organ or have gestational complications, including recurrent miscarriages or fetal losses. Immune thrombocytopenia, not usually severe, may be superimposed on the thrombotic complications. Some patients with ITP also have anti-phospholipid antibodies but do not necessarily develop thrombotic or gestational complications as a result.
Henoch-Schonlein purpura (HSP) is a rare disease involving the small blood vessels (capillaries) that is usually self-limited. It is the most common form of inflammation involving small vessels (vasculitis) occurring in childhood. The symptoms usually begin suddenly and may include headache, fever, loss of appetite, cramping abdominal pain and/or joint pain. The resemblance to ITP is that red or purple spots typically appear on the skin that may resemble bruises, but thrombocytopenia is quite uncommon. A major diagnostic clue to HSP is that the signs are predominantly on the lower extremities rather than distributed all over. Furthermore, unlike ITP, the “bruises” are often palpable. Inflammatory changes an also develop in the joints, kidneys, digestive system and, in rare cases, the brain and spinal cord (central nervous system). The cause of HSP has not been established, although research suggests that it may be an autoimmune disease, such as a severe allergic reaction to offending substances (e.g., foods or drugs). (For more information on this disorder, choose “Henoch-Schonlein purpura” as your search term in the Rare Disease Database).
Anti-thyroid autoantibodies are detected commonly in patients with ITP, especially in young women. Assessment of thyroid function may therefore be indicated in many patients especially women of child-bearing age. Other autoantibodies such as the ANA are reported less commonly but may be important if strongly positive.
Most patients with ITP present with some form of bleeding, typically in the skin. On occasion, a low platelet count may be detected incidentally by a complete blood count (CBC) ordered for other purposes such as for infection, before surgery or on a routine checkup in an individual without apparent symptoms (asymptomatic). Most ITP patients have “isolated” thrombocytopenia with normal appearing red cells and white cells, but anemia can result from bleeding and iron deficiency and changes in the white blood cell count can occur with recent infection. If there are lower or higher than normal WBC or RBC counts, the chance this is NOT ITP increases substantially. Secondary forms of ITP are suspected when an individual has a history of recurrent infections, fever or weight loss, enlarged lymph nodes, joint pains, is post vaccination, etc.
The diagnosis of ITP is usually made by excluding other causes of isolated thrombocytopenia, including certain medications and disorders that affect the bone marrow and reduce platelet production. Inspection of the blood smear under the microscope will verify platelets are truly reduced in number and not simply clumped together or too big to be counted by automated machines as platelets. When clumping is seen, the platelet count should be measured using blood collected in a blue top (citrate) tube or directly from the finger to establish whether the platelet count in the body is low. The platelets in ITP are normal in size or the size may vary with some platelets somewhat larger than normal, but not uniformly very small or exceeding large (giant platelets) as seen in some hereditary thrombocytopenias. The red blood cells and white blood cells are usually normal in number and appear normal, helping to exclude consideration of leukemia or myelodysplasia, among other causes of thrombocytopenia. The presence of unusual appearing white blood cells in the blood or additional abnormalities in the blood counts might indicate the need for other testing including a bone marrow examination to exclude other causes of impaired platelet production.
In a patient who is in good health, who has not recently started a new medication, and is found to have thrombocytopenia with no other abnormality identified in a complete blood count or upon inspection of the blood smear, has no family history of thrombocytopenia, and, if available, has a normal platelet count in the past, the diagnosis of new onset ITP is likely. There is no definitive test (including measurement of platelet autoantibodies) to make the diagnosis or to exclude the diagnosis of ITP. However, a robust response to ITP-specific treatments such as intravenous immunoglobulin (IVIG) or glucocorticoids (described below) provides strong evidence in favor of the diagnosis.
Management of adults depends on severity of symptoms, platelet count, age, lifestyle, response to therapy and its side effects, the presence of other medical issues that affect the risks of bleeding and other complications including medications taken, quality of life as discussed above, and the personal preferences of both the patient/their caregivers and treating physicians as they relate to work, lifestyle, family support and expectations, among other factors.
While there is no well-established treatment that cures patients with ITP, fortunately almost all patients find that their platelet count will improve following treatment. What proves difficult for many ITP patients who benefit from treatment is finding the treatment that works for them without unwanted side effects and that they can access. In some individuals, especially children, the disease can go into remission usually for the remainder of a person’s life. However, ITP can also recur at any time and there is currently no way to reliably predict the course of the disease other than the clearly better prognosis of children compared to adults. Changes in diet or lifestyle may improve (or worsen) the sense of well-being, but the impact on platelet count is less certain. It is also important that the patient and physician have an ongoing dialogue involving all concerns and decisions concerning treatment options including whether any treatment is needed.
For children, management at disease onset is often expectant based on the degree of and risk of bleeding rather than the platelet count. Treatment is more routinely administered in the chronic phase and is most commonly thrombopoietin (TPO) agents in preference to other second line agents. Risk of bleeding and side effects of treatments such as corticosteroids differs from adults and depends on the child’s age. Input from the child’s caregiver and child to the extent possible, also factors into treatment decisions. Extensive studies of children have explored treatment of those with chronic disease and a recent study of children with ITP at presentation, the TIKI trial, validated the expectant approach in children with only grade 1 and 2 bleeding but simultaneously demonstrated a degree of curative effect following IVIG treatment.
Criteria for Treatment
In most children and some adults, therapy may not be necessary at the time they first see their physician and the disorder may resolve spontaneously. The decision to initiate treatment depends on the severity of bleeding, the severity of the thrombocytopenia (especially in adults) the age of the patient (increased risk of bleeding in the elderly), coincidental disorders that might predispose to bleeding (tendency to fall, concurrent anti-platelet drugs or anticoagulants), lifestyle (such as young and athletic or jobs such as construction) and risks, side effects and costs and time away from work required for each intervention. In addition, after careful and comprehensive investigation, treatment may also be indicated to improve quality of life. These factors contribute to deciding if treatment is indicated and which treatment to use.
The goal of therapy in adults and children is to prevent bleeding, stabilize and hopefully improve the platelet count, and help restore the patient’s ability to have a normal lifestyle. When treatment is deemed necessary, there are many options that have proven successful. Treatments differ in likelihood of benefit and attendant risks. Some are considered more toxic and are, therefore, generally deferred unless it is proven they are needed. Treatments also differ in their intended effect: e.g., short term increase in platelets above dangerous levels versus long-term maintenance of a stable platelet count versus cure. It is important to understand both the success rate and potential side effects before beginning any form of treatment. Hematologists may recommend combining several treatments that act in different ways to increase their success rate and minimize their side effects by avoiding the highest doses required when agents are used individually.
First Line/Emergency Therapy
Treatment with corticosteroids (e.g., high doses of prednisone, dexamethasone, methylprednisolone) is usually the mainstay of initial therapy. These drugs function by initially suppressing the clearance of antibody-coated platelets and perhaps with more prolonged use by increasing platelet production. They may also decrease the risk of bleeding by improving the function of the cells lining the blood vessels. Use of high doses of dexamethasone for several days may accelerate response compared with daily oral prednisone and may have less lasting toxicity because of its 4-day course of treatment. However, tolerability of high-dose dexamethasone may be lower than that of prednisone and certain patients will refuse to use it again. In general, the duration and dose of corticosteroids should be minimized (less than 6 weeks) because of their immediate and long-term side effects. Therefore, corticosteroids are used to control the disease until a transition can been made to other forms of treatment in patients who do not achieve a spontaneous stabilization at an adequate count or a remission.
If platelet counts do not improve after corticosteroid treatment or when individuals present with severe bleeding, initial treatment includes adding intravenous immunoglobulin (IVIG). IVIG is typically given as needed every 2-4 weeks based on the platelet count and signs of bleeding, but rarely leads to a cure.
Platelet transfusions are reserved for the most emergent situations because they are likely to be destroyed relatively quickly by the autoantibodies. Even more than steroids, they may be widely overused according to a recent study.
The orphan drug anti-D (WinRho SDF, Rhophylac), a specific form of gamma globulin, was approved by the U.S. Food and Drug Administration (FDA) to treat ITP in individuals who are red blood cell RhD antigen positive, do not already have antibodies on their red cells and have not undergone splenectomy. The drug can be used repeatedly, including in children who have newly diagnosed, persistent or chronic ITP. However, concerns have been raised because of a small fraction of individuals who have had severe side effects from brisk red cell destruction and its consequences soon after infusion.
Response can be based on cessation of bleeding (clinical response) and/or attaining a platelet count above 20-30,000/µl or higher for procedures or delivery (partial response). A response in platelets to greater than 100,000/µL is usually termed a complete response, but this should not be confused with cure when a patient is on or has recently completed therapy. Failure to respond to first line therapy, as opposed to responding but then relapsing, should prompt reconsideration of the diagnosis of ITP.
Second Line Therapy
The criteria for determining whether second line therapy is needed are the same as those involving initiation of treatment plus patients with suboptimal and/or short-lived responses to first line approaches. As mentioned, corticosteroids should be used for the shortest duration possible (ideally less than 6 weeks) to achieve these objectives and to provide a bridge to less toxic alternatives if treatment continues to be required. Many adults and some children will need long-term management because their platelet count fell once the dose of corticosteroids is tapered and IVIG is stopped.
One second-line option is thrombopoietin receptor agonists (TPO-RAs). TPO-RAs function by stimulating the body’s production of platelets by megakaryocytes in the bone marrow, which release proplatelets that mature into platelets. By increasing the rate at which platelets are produced in the body, TPO-RAs may overcome the heightened rate of platelet destruction caused by antiplatelet antibodies and their ability to impair megakaryocyte platelet production. Three TPO-RAs are approved by the FDA for use in ITP: eltrombopag (Promacta/Revolade) romiplostim (Nplate) and avatrombopag (Doptelet); only the first two are approved in children. Other TPO-RAs are in development or approved for related indications, such as thrombocytopenia in liver disease.
In 2008, the FDA approved both romiplostim (Nplate) and eltrombopag (Promacta) to treat both children and adults with ITP who have had an insufficient response to corticosteroids, immunoglobulins or splenectomy. Romiplostim is typically given by weekly subcutaneous injection, most often in a physician’s office. Eltrombopag has two extremely important dietary restrictions that are needed to allow this oral agent, which is administered once daily, to be effective: it must be taken on an empty stomach meaning no food for at least 1 hour before and 2 hours after and no high calcium food such as dairy, for 4 hours before and 4 hours after ingestion. In 2015, eltrombopag was approved for the treatment of children 1 year and older with ITP who have had an insufficient response to corticosteroids, immunoglobulins or splenectomy; romiplostim was similarly approved in late 2018. Response rate, depending upon the definition of response, to both agents ranges from 40-80% and, once a stable response is obtained, is generally durable with ongoing treatment. The drugs are generally well tolerated and long-term safety studies have mitigated initial concerns about thrombosis and especially bone marrow scarring. Some patients (an unknown percent but perhaps approaching 30%) will experience sufficient improvement in their ITP over 1-2 years taking a TPO agent to discontinue and remain off treatment.
In 2019, the FDA approved avatrombopag (Doptelet) to treat ITP in adults with chronic ITP who have had insufficient response to a previous treatment. This is the only oral TPO-RA medication approved to treat ITP that can be taken with food. Avatrombopag is generally considered safe and well tolerated. Recent data suggests that patients who fail to respond (or who have a side effect) to one oral TPO-RA may show a good response (or not develop the same side effect) when they switch to an alternative TPO-RA.
Another option is anti-CD20 antibody, rituximab (Rituxan) which now has several biosimilars although their mechanism of action remains poorly understood. Provided intravenously, the standard dose and administration is one infusion every 7 days for four weeks consecutively at 375mg/m2 per infusion. Other approaches have been used including 100mg weekly x 4 and 1000mg biweekly x 2. About half of ITP patients respond initially. Women of child-bearing age of duration of ITP < 1-2 years have an over 50% cure rate but <20% of the remaining patients are cured in long-term (5 year) outcome studies. Rituximab is generally well tolerated but infusion reactions can occur; premeditation including steroids is very good at mitigating this problem. Administration may be repeated when a durable response has been seen but there is a relapse, but a better response the second time is very unlikely. Concern over repetitive administration of this immunosuppressant may be warranted as a cause of hypogammaglobulinemia. Recently, use of Rituxan is tempered because the drug prevents antibody response to vaccines, e.g., against SARS-CoV2, for at least 6-12 months after administration. Studies have approached combining rituximab with other agents especially dexamethasone because of the latter’s anti-plasma cell effects.
A third option,Tavalisse (fostamatinib disodium hexahydrate) was approved in 2018 by the FDA for the treatment of thrombocytopenia in adults with ITP who have had insufficient response to a previous treatment; because of concerns about adverse effects on the growth plate, it should not be given to children. Approximately 20% of patients who are refractory to other forms of management responded based on pre-specified criteria, but, importantly, almost 40% did so using less stringent but clinically meaningful endpoints and most did so within several weeks of initial administration. The drug has several side effects (hypertension, diarrhea, headache and abnormal liver tests). One advantage is that it has the lowest reported risk of thrombosis of any licensed treatment of ITP and has anti-inflammatory effects as well, although additional clinical data is needed to confirm these findings.
The 4th main second-line option is splenectomy (typically laparoscopic), because the spleen plays a major role in destroying antibody-covered platelets and contributes to making antiplatelet antibodies. Splenectomy improves platelet counts in approximately 80% of patients initially and can induce a long-term remission in 60%. The high long-term success rate must be weighed against the small but real increased risk of thrombosis and serious infection, which necessitates appropriate vaccinations and urgent evaluation for serious febrile illnesses. Recent guidelines recommend deferral of splenectomy for at least a year from diagnosis to determine if a patient will go into remission. However, splenectomy remains an option in patients who fail other forms of treatment or in resource challenged areas where more expensive alternatives which require repeated administration are not available. As mentioned, combinations of agents are often used to increase response and lessen toxicity.
Third Line Therapy
A small percentage of patients fail to respond or tolerate first- or second-line treatments. For those, options include dapsone, Imuran (azathioprine), Cytoxan (cyclophosphamide), Sandimmune (cyclosporine), Danocrine (danazol), Cellcept (mycophenolate mofetil), Vincristine (vinca alkaloids) or combinations of these and first or second-line agents. It is important to recognize that the division between 2nd and 3rd line therapy may be somewhat arbitrary and many clinicians would consider, for example, mycophenolate mofetil a second line treatment.
Several novel forms of treatment are in clinical trials such as FcRn inhibitors, BTK inhibitors, and inhibitors of complement.
If the patient has antibodies or evidence of Helicobacter pylori infection, treatment with antibiotics and proton pump inhibitors to eradicate the infection may ameliorate the condition. However, antibiotic associated remission of ITP is much more common in Asia i.e., Japan, and in some parts of Europe, especially Italy, than in patients who have lived their entire life in North America.
Some patients report improved health-related quality of life with complementary therapies such as vitamins, supplements, diet changes, herbs such as papaya and turmeric, meditation and visualization, and energy work such as Reiki. However, there are no controlled trials in ITP patients demonstrating utility or safety of any of these agents.
Prominent complaints in patients with ITP include not only bleeding, thrombosis, and side effects of medication, especially steroids, but also persistent symptoms of fatigue and impaired health-related quality of life. The I-WISh 1.0 study showed these often persist even if the ITP is better and successful treatment of platelets does not always ameliorate these symptoms.
Certain measures can be taken to help reduce bleeding in addition to raising the platelet count. These include use of anti-fibrinolytics for heavy menses or problematic epistaxis; iron and thyroid replacement if needed; hormonal therapy (especially progesterone-based to not worsen the ITP with estrogen) for heavy menses; exploration of viral PCRs for ongoing infection such as CMV; and attention to gingival hygiene for gum bleeding. Similarly, certain approaches may improve quality of life without necessarily affecting the platelet count.
The Platelet Disorder Support Association (PDSA) is dedicated to enhancing the lives of people with ITP and other platelet disorders through education, advocacy, research and support. The PDSA connects ITP patients and caregivers with life-altering programs and support. PDSA is committed to building awareness, educating the global community and providing critical connections and resources that empower patients to take charge of their disease and encourage practitioners to exercise patient-centered medical care. The PDSA collaborates with other patient advocacy groups, researchers and government agencies to drive public policy, develop new treatment options and support research to find a cure. www.pdsa.org
The PDSA website lists the most current ITP clinical trials at https://pdsa.org/clinical-trials.html
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:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
For information about clinical trials sponsored by private sources, contact:
For information about clinical trials conducted in Europe, contact:
For information about clinical trials conducted in Canada, contact: https://www.centerwatch.com/clinical-trials/listings/location/international/Canada/
Algazy KM. Idiopathic Thrombocytopenic Purpura. In: NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:415-16.
Marini I, Uzun G, Jamal K, Bakchoul T. Treatment of drug-induced immune thrombocytopenias. Haematologica. 2022 Jun 1;107(6):1264-1277. doi: 10.3324/haematol.2021.279484
Neunert C, et al. American Society of Hematology 2019 guidelines for immune thrombocytopenia. Blood Advances. 2019;3(23);3829-3866.
ProvanD et al. Updated international consensus report on the investigation and management of primary immune thrombocytopenia. Blood Advances.2019:3 (22): 3780-3817.
Kistangari G and McCrae KR. Immune thrombocytopenia. Hematology/Oncology Clinics of North America. 2013;3:495-520. doi:10.1016/j.hoc.2013.03.001
Perdomo J, et al. Quinine-induced thrombocytopenia: Drug-dependent GPIb/IX antibodies inhibit megakaryocyte and proplatelet production in vitro. Blood. 2011;117 (22):5975-86.
Chouhan JD, Herrington JD. Treatment options for chronic refractory immune thrombocytopenia in adults: focus on romiplostim and eltrombopag. Pharmacotherapy. 2010;30(7):666-83.
Deane S, Teuber SS, Gershwin ME. The geoepidemiology of immune thrombocytopenic purpura. Autoimmun Rev. 2010;9(5):A34.
Terrell DR, et al. The incidence of immune thrombocytopenic purpura in children and adults: A critical review of published reports” Am J Hematol. 2010 Mar;85(3):174-80.
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Cines DB, Liebman HA. The immune thrombocytopenia syndrome: a disorder of diverse pathogenesis and clinical presentation. Hematol Oncol Clin North Am. 2009;23(6):1155-61.
Fogarty PF. Chronic immune thrombocytopenia in adults: epidemiology and clinical presentation. Hematol Oncol Clin North Am. 2009;23(6):1213-21.
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Platelet Disorder Support Association. ITP & Genetics. https://pdsa.org/genetics Accessed July 11, 2022.
Platelet Disorder Support Association. Substance-Induced ITP. https://pdsa.org/substance-induced-thrombocytopenia.html Accessed July 11, 2022.
Platelet Disorder Support Association. About ITP. http://pdsa.org/about-itp.html Accessed July 11, 2022.
Platelet Disorder Support Association. Information about other platelet disorders. http://pdsa.org/resources/other-platelet-disorders.html Accessed July 11, 2022.
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McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). The Johns Hopkins University. Thrombocytopenic Purpura, Autoimmune. Entry Number; 188030. Updated 03/24/2009. Available at http://omim.org/entry/188030 Accessed July 11, 2022.
NORD strives to open new assistance programs as funding allows. If we don’t have a program for you now, please continue to check back with us.
NORD and MedicAlert Foundation have teamed up on a new program to provide protection to rare disease patients in emergency situations.Learn more https://rarediseases.org/patient-assistance-programs/medicalert-assistance-program/
Ensuring that patients and caregivers are armed with the tools they need to live their best lives while managing their rare condition is a vital part of NORD’s mission.Learn more https://rarediseases.org/patient-assistance-programs/rare-disease-educational-support/
This first-of-its-kind assistance program is designed for caregivers of a child or adult diagnosed with a rare disorder.Learn more https://rarediseases.org/patient-assistance-programs/caregiver-respite/
Powered by NORD, the IAMRARE Registry Platform® is driving transformative change in the study of rare disease. With input from doctors, researchers, and the US Food & Drug Administration, NORD has created IAMRARE to facilitate patient-powered natural history studies to shape rare disease research and treatments. The ultimate goal of IAMRARE is to unite patients and research communities in the improvement of care and drug development.