Immune thrombocytopenia

• Immune thrombocytopenia (ITP) is an acquired autoimmune disorder in which immunoglobulin G (IgG) autoantibodies and disordered T-cell immunity shorten platelet survival and suppress megakaryocyte production, so the platelet count falls without anaemia or leukopenia.
• It is a diagnosis of exclusion: isolated thrombocytopenia with a normal blood count otherwise, a normal peripheral blood film, and no other explanation.
• Petechiae, purpura and mucosal bleeding (epistaxis, gum bleeding, heavy periods, gastrointestinal bleeding) are the usual manifestations; many patients with counts above 50 × 10^9/L have no symptoms at all.
• In children it usually follows a viral infection and remits within weeks; in adults it is usually chronic and insidious.
• Treatment is guided by bleeding, not the platelet number alone: observation when counts are above about 30 × 10^9/L, treatment below that or when there is mucosal bleeding; first-line corticosteroids, with intravenous immunoglobulin (IVIG), anti-D, thrombopoietin receptor agonists (TPO-RAs), rituximab and splenectomy used in defined situations.
• The 2019 American Society of Hematology (ASH) guideline sets the thresholds and drug choices discussed below; a focused 2026 ASH update changes initial and second-line therapy for adults with primary ITP, so check the latest local guidance.

By the end of this page you should be able to:

1. Explain why the platelet count falls in ITP, naming both peripheral destruction and impaired production.
2. Distinguish primary ITP from secondary ITP and name the common secondary causes.
3. Contrast acute ITP in children with chronic ITP in adults, including the typical time course.
4. Take a history, examine a patient, and read the blood count and film to diagnose ITP and exclude its mimics.
5. Interpret the guideline thresholds for observation versus treatment and choose first-line and second-line therapy.
6. Manage an ITP emergency, including pregnancy and neonatal considerations.
7. Recognise the situations in which tests (HIV, hepatitis C, H. pylori, bone marrow) are justified.

The International Working Group classifies ITP by duration. Newly diagnosed ITP is the first 3 months after diagnosis; persistent ITP is present for 3 to 12 months; chronic ITP lasts more than 12 months. ^[3] Earlier terminology ("idiopathic thrombocytopenic purpura", "immune thrombocytopenic purpura") is still widely used, but the preferred term is immune thrombocytopenia. The old term "refractory ITP" is best reserved for patients who have failed splenectomy and one or more medical therapies.

Primary ITP is the diagnosis when no trigger is found. Secondary ITP occurs when thrombocytopenia is a manifestation of an underlying condition. The distinction matters because treatment of secondary ITP is often directed at that condition (for example, antiviral therapy for hepatitis C or HIV) rather than, or as well as, the platelet count. ^[2]

ITP can occur at any age, with peaks in early childhood and in older adults. Estimates of incidence differ slightly between authoritative sources. The 2019 ASH guideline gives 2 to 5 per 100 000 persons in the general population, ^[2] while the 2026 ASH update gives 1 to 6 per 100 000 adults. ^[4] In children, a low-resource-region guideline adapted for Egypt gives 1.9 to 6.4 per 100 000 children per year. ^[5]

Adults with ITP have a 1.3- to 2.2-fold higher mortality than the general population, driven by cardiovascular disease, infection and bleeding. ^[2] The risk is concentrated in patients 60 years and older. ^[1] In children, the annual incidence figures above apply, and spontaneous remission within weeks to months is the rule rather than the exception.

Primary ITP has no single identified cause. The favoured model is loss of immunological tolerance to platelet antigens, with both B-cell and T-cell abnormalities. There is no known modifiable risk factor.

Secondary ITP is said to account for a minority of cases. The important associations, all of which need to be considered at diagnosis:

• Infections: HIV, hepatitis C, hepatitis B, Helicobacter pylori, Epstein-Barr virus, cytomegalovirus, parvovirus, and (classically in children) preceding viral upper respiratory infection. Post-vaccination ITP is rare, and a prospective case-control study found no increased odds of ITP following vaccination in adults in the previous 6 to 12 months (odds ratio 1.0, 95% confidence interval 0.7 to 1.4). ^[2]
• Autoimmune disease: systemic lupus erythematosus and the antiphospholipid syndrome; thyroid disease.
• Lymphoproliferative and haematological disease: chronic lymphocytic leukaemia, lymphoma, myelodysplastic syndrome.
• Drugs: heparin (as the distinct heparin-induced thrombocytopenia syndrome, with thrombosis rather than bleeding), alemtuzumab, PD-1 inhibitors, abciximab, valproate, quinine (including tonic water), and many chemotherapy agents. Drug-induced thrombocytopenia is usually immune in nature but is often clinically indistinguishable.
• Pregnancy: gestational thrombocytopenia and pregnancy-specific hypertensive disorders are differential diagnoses; ITP itself is rare in pregnancy.
• Vaccines: live attenuated vaccines, especially measles-mumps-rubella (MMR), have been associated with ITP in children. ^[1]

Risk factors for chronic ITP in children include older age, a higher platelet count at presentation, and absence of a preceding infection. ^[2] A family history of autoimmune disease has not been shown to predict ITP in a prospective cohort study.

The pathophysiology of ITP is complex and still incompletely understood, but two themes are well established. ^[1]

1. Peripheral destruction of platelets. IgG autoantibodies bind to platelet surface glycoproteins, most often GPIIb/IIIa and GPIb/IX. ^[1] The antibody-coated platelets are cleared by macrophages of the reticuloendothelial system. The spleen is the primary site of antibody production and the dominant organ for clearance of IgG-coated platelets; in a minority of patients hepatic clearance predominates. ^[1] Clearance is mediated mainly by the low-affinity Fc gamma receptors FcγRIIA and FcγRIIIA. ^[1] Complement-mediated and desialylation-mediated clearance are additional pathways, and anti-GPIb/IX antibodies have been associated with a poorer response to IVIG, consistent with non-Fc-mediated mechanisms. ^[1] T-cell-mediated cytotoxicity may also contribute. ^[1]

2. Impaired platelet production. About 40% of patients with chronic ITP have a reduced platelet turnover on kinetic studies, and only 10% to 15% of adults achieve a durable remission with corticosteroids. ^[1] Autoantibodies (and T cells) bind megakaryocytes in the bone marrow and suppress megakaryocyte maturation and platelet release, producing non-classical (para-apoptotic) megakaryocyte changes on electron microscopy. ^[1] This is why stimulating megakaryopoiesis with TPO receptor agonists works.

Anti-platelet antibodies cannot be detected in up to half of people with ITP, most likely for technical reasons (assays are configured for GPIIb/IIIa and GPIb/IX and have variable sensitivity). ^[1] Their absence does not exclude ITP. Cross-reactivity explains many secondary cases: infections such as HCV, HIV and H. pylori can generate antibodies that cross-react with platelet antigens, or immune complexes that bind platelet Fc receptors. ^[1]

A striking clinical feature is the poor correlation between platelet count and bleeding. Most people with counts above 50 × 10^9/L have no problem bleeding at all, while severe bleeding (including intracranial haemorrhage) is uncommon and occurs mainly below 20 × 10^9/L. ^[1] In children with newly diagnosed ITP only 0% to 4% have severe bleeding requiring intervention, and intracranial haemorrhage occurs in roughly 0% to 1%. ^[3][5]

Presentation can be with no symptoms at all, an incidental low count, or bleeding. Typical symptoms are easy bruising, petechiae and purpura on the limbs and trunk, epistaxis, gingival bleeding, menorrhagia, haematuria and gastrointestinal bleeding. Intracranial haemorrhage is the most feared complication but is rare. Fatigue is reported in 22% to 45% of patients and is an important quality-of-life issue in its own right. ^[2]

The clinical picture splits by age. Children typically present abruptly (acute ITP), 1 to 2 weeks after a viral infection or 2 to 6 weeks after MMR vaccination, and recover spontaneously within weeks. ^[1] Adults usually have an insidious onset with no preceding illness and a chronic course. ^[1]

Systemic symptoms (fever, weight loss, lymphadenopathy, hepatosplenomegaly) point away from primary ITP toward infection, autoimmune disease, lymphoproliferative disease or (rarely) malignancy. ^[2] A previous infection is reported in about 55% of paediatric cases. ^[3]

Examination is usually normal apart from bleeding manifestations (petechiae and purpura). ^[2] Moderate or massive splenomegaly, lymphadenopathy, hepatomegaly or constitutional symptoms suggest an alternative diagnosis (HIV, chronic liver disease, systemic lupus erythematosus, lysosomal storage disease or lymphoproliferative disease). ^[2] The spleen is not enlarged in uncomplicated ITP. A family history of bleeding, skeletal or renal abnormalities, hearing loss or thrombocytopenia since childhood points toward an inherited thrombocytopenia rather than ITP. ^[2]

ITP is a diagnosis of exclusion. The problem for the clinician is distinguishing it from the many other causes of a low platelet count. The table lists the frequent alternative causes identified by the 2019 international consensus report. ^[3]

• Full blood count: isolated thrombocytopenia. The white cell count and haemoglobin should be normal; abnormalities should prompt further testing. Microcytic anaemia proportional to the bleeding may indicate iron deficiency.
• Peripheral blood film, reviewed by a haematologist or pathologist: this excludes pseudothrombocytopenia (EDTA-dependent platelet clumping), schistocytes (thrombotic thrombocytopenic purpura, haemolytic-uraemic syndrome), giant platelets (inherited thrombocytopenia) and leukaemic blasts.
• History: bleeding after prior surgery, dental work or trauma; prior blood counts; drugs and toxin exposure (including over-the-counter and tonic water); travel; vaccinations; infections; needle-stick exposure if indicated; transfusions; heavy menstrual bleeding; family history.
• Physical examination: looking for the alternative diagnoses listed above.
• Blood group (Rh): essential if anti-D therapy is a possibility.
• HIV and hepatitis C (and hepatitis B) testing at baseline in adults, regardless of local prevalence and personal risk factors; viral testing before any blood product (including IVIG). ^[3] These infections can be clinically indistinguishable from ITP and may precede other symptoms by years; controlling them can produce complete remission. ^[3]
• H. pylori testing (urea breath test or stool antigen test; serology is less reliable and can be falsely positive after IVIG) in adults with typical ITP, in those with digestive symptoms and in those from areas of high prevalence. Routine testing outside these situations is not supported. ^[2][3] Eradication therapy should be given when H. pylori is found. ^[2]
• Quantitative immunoglobulin levels (IgG, IgA, IgM): useful to exclude immune deficiency syndromes (including common variable immunodeficiency) and before IVIG. ^[3]
• Direct antiglobulin (Coombs) test (DAT): positive in about 20% of patients with ITP. ^[3] If positive, assess haemolysis (haptoglobin, lactate dehydrogenase, bilirubin, reticulocytes) to exclude Evans syndrome. Essential before anti-D because active haemolysis is a contraindication.
• Antinuclear antibodies: positive in about 9% of children and 33% of adults with ITP; may predict chronicity and can guide treatment, but routine testing is not mandatory. ^[3]
• Thyroid function and anti-thyroid antibodies: ITP has been associated with hyperthyroidism in 8% to 14% of patients. ^[3]

• Glycoprotein-specific platelet antibody assays (MAIPA, modified antigen capture ELISA): high specificity, low sensitivity; may help in complex cases but should be performed in reference laboratories. ^[3] Platelet-associated IgG is unhelpful because it is raised in both immune and non-immune thrombocytopenia. ^[3]
• Antiphospholipid antibodies: present in up to 25% to 30% of adults with otherwise typical ITP (up to 46% in some series) but do not influence treatment response. Test when there are features of the antiphospholipid syndrome. ^[3]
• Bone marrow examination: not needed for typical ITP. ^[2][3] Consider it in adults with systemic symptoms, abnormal signs, or features suggesting another diagnosis; before splenectomy; in non-responders to corticosteroids or IVIG, especially older adults (where next-generation sequencing panels for clonal disease should be considered); or when the count or morphology is abnormal. ^[3] If performed it should include aspirate, biopsy, flow cytometry and cytogenetics. ^[3] In children, bone marrow examination is unnecessary with typical features, including before corticosteroid therapy, and is reserved for atypical or refractory disease. ^[2][5]
• Other tests that do not establish ITP in typical adults include TPO level, reticulated platelets/immature platelet fraction (not standardised), routine coagulation tests (helpful only to exclude DIC or thrombotic microangiopathy by ADAMTS13 testing) and H. pylori testing in children with chronic ITP unless they are in at-risk populations. ^[3][5]

ITP remains a diagnosis of exclusion: no "gold standard" test confirms it. Response to ITP-directed therapy (IVIG, anti-D or corticosteroids) supports the diagnosis but does not exclude secondary ITP, since many secondary forms also respond to IVIG. ^[2]

Classical ITP features are an isolated platelet count less than 100 × 10^9/L with normal white cell count and haemoglobin, plus a normal peripheral blood film. If therapy is given, the platelet count should be monitored for response as a diagnostic aid. ^[2]

Severity terms used in guidelines:

• Newly diagnosed: 0 to 3 months after diagnosis
• Persistent: more than 3 to 12 months
• Chronic: more than 12 months
• Corticosteroid-dependent: ongoing need for continuous prednisone more than 5 mg per day (or equivalent), or frequent courses, to maintain a platelet count of at least 30 × 10^9/L or avoid bleeding. ^[2]
• Durable response: platelet count at least 30 × 10^9/L with at least a doubling of baseline at 6 months. ^[2]
• Major bleeding: WHO grade 3 or 4 bleeding; Buchanan "severe" grade; Bolton-Maggs and Moon "major" bleeding; IBLS grade 2 or higher; or life-threatening or intracranial bleeding. ^[2]

Standardised bleeding scores are also useful. The updated paediatric scale grades bleeding from grade 1 (minor petechiae) to grade 4 (severe mucosal bleeding leading to a fall in haemoglobin of more than 2 g/dL or suspected internal haemorrhage). ^[6]

The objectives are to prevent severe bleeding, keep the platelet count above 20 to 30 × 10^9/L (with higher targets for the active, the elderly over 60, those with comorbidity and those on anticoagulants), use the least toxic therapy, and optimise quality of life. ^[3] Therapy can usually be given as an outpatient unless there is active bleeding, anticoagulation, close monitoring needs, or a first presentation with platelets under 20 × 10^9/L. ^[3]

The International Consensus Report places a practical treatment threshold of about 20 × 10^9/L for adults without bleeding or comorbidity, since bleeding risk rises below that level, and is rare above 20 × 10^9/L in the absence of other risk factors. ^[3] The ASH guideline is more conservative about platelet numbers alone: corticosteroids are suggested for adults below 30 × 10^9/L and observation recommended above 30 × 10^9/L, with exceptions for high-risk patients. ^[2]

The 2026 focused ASH update for adults with primary ITP suggests initial therapy that adds a second agent to corticosteroids - either rituximab plus corticosteroids, or a TPO receptor agonist plus corticosteroids (with or without IVIG) - rather than corticosteroids alone or mycophenolate plus corticosteroids. ^[4] It recommends a thrombopoietic agent, or suggests rituximab, for adults who need additional therapy after corticosteroids. ^[4] The 2019 threshold for starting treatment (below about 30 × 10^9/L) and the durable corticosteroid duration limit (no more than 6 weeks) are unchanged. ^[4]

Corticosteroids remain the standard initial treatment for adults who need treatment. ^[2][3] ASH 2019 offers a choice between prednisone 0.5 to 2.0 mg/kg per day or dexamethasone 40 mg per day for 4 days. ^[2] The international consensus uses prednis(ol)one 1 to 2 mg/kg per day, maximum 80 mg (even in those weighing more than 80 kg), for 2 weeks with a maximum of 3 weeks, or dexamethasone 40 mg/day for 4 days repeated up to 3 times. ^[3] If a response is seen (platelets above 50 × 10^9/L), prednisolone should be tapered with the aim of stopping by 6 weeks (maximum 8 weeks), even if the count drops during the taper; with no response in 2 weeks, taper rapidly over 1 week and stop. ^[3] Corticosteroids longer than 6 weeks should be avoided to limit side effects (hypertension, hyperglycaemia, mood and sleep disturbance, gastric ulceration, glaucoma, myopathy, osteoporosis). ^[2] High-quality randomised evidence comparing prednisone with dexamethasone is limited, but high-dose dexamethasone tends to give faster early responses. ^[3]

Grade 1B recommendation: testing for HCV and HIV is recommended in all adults with suspected ITP. ^[2]

Intravenous immunoglobulin (IVIG) is reserved for bleeding, a high risk of bleeding, an upcoming procedure, or failure of corticosteroids; it is used together with corticosteroids in life-threatening bleeding. ^[2][3] Usual regimens are 1 g/kg on 1 or 2 consecutive days, or 0.4 g/kg per day for 5 days. ^[2][3] IVIG raises the platelet count in roughly 70% to 80% of patients, often within 1 to 2 days, but responses last only 3 to 4 weeks. ^[1][3] Side effects include headache, nausea and vomiting (which must be distinguished from intracranial bleeding) and, rarely, acute renal failure with sucrose-containing products. ^[1][3]

Intravenous anti-D (50 to 75 microg/kg once) can be used in Rh(D)-positive, non-splenectomised patients with haemoglobin above 10 g/dL and a negative DAT, where it is available. ^[2][3] About three-quarters (78% in the largest reported series) of patients achieve a platelet rise of at least 20 × 10^9/L. ^[1] It carries a black-box warning for intravascular haemolysis, acute renal failure, disseminated intravascular coagulation and, rarely, death; it is not available in Europe. ^[2][3] It should not be used with active haemolysis or haemoglobin under 10 g/dL. ^[1]

TPO receptor agonists and rituximab are not initial therapy according to the 2019 consensus (except added to corticosteroids in a patient who is steroid-dependent or unresponsive, as in the 2026 update). ^[3][4]

For adults newly diagnosed with ITP and counts under 20 × 10^9/L and minor or no bleeding, admission is suggested rather than outpatient care; above 20 × 10^9/L, outpatient management is preferred, although relative contraindications, diagnostic uncertainty, social concerns, comorbidity or significant mucosal bleeding can shift the decision either way. ^[2]

The international consensus recommends a follow-up with a haematologist within 24 to 72 hours of diagnosis or relapse, and 2 weeks of corticosteroid pre-treatment with acyclovir may be given with dexamethasone to minimise herpes reactivation. ^[2][3]

Most adults relapse when corticosteroids are stopped, and continuing low-dose corticosteroids indefinitely is discouraged because toxicity outweighs benefit. ^[3] Second-line options:

• Thrombopoietin receptor agonists (TPO-RAs): romiplostim, eltrombopag and avatrombopag increase platelet production. Response rates above 60% are reported in splenectomised and non-splenectomised adults, and treatment-free remission in about 15% to 30% of chronic patients and nearly one-third of newly diagnosed patients. ^[3] Romiplostim is given subcutaneously at 1 microg/kg per week, adjustable to 10 microg/kg per week; ^[3] eltrombopag 25 or 50 mg daily (maximum 75 mg/day) taken 2 hours before or 4 hours after polyvalent cations, with liver monitoring; ^[3] avatrombopag 20 mg daily (up to 40 mg daily). ^[3] Side effects include hepatotoxicity (eltrombopag), a 6% rate of arterial or venous thrombosis in long-term extension studies of romiplostim and eltrombopag (higher over age 60 in romiplostim series), and reversible bone marrow fibrosis or in a few patients. ^[3] Patients who fail one TPO-RA may respond to another. ^[3]
• Rituximab: 375 mg/m2 weekly for 4 weeks. ^[3][4] Initial responses in 60% to 80%, with 21% maintaining remission at 5 years. ^[3] Screen for hepatitis B beforehand (reactivation is a black-box risk), and remember rituximab can impair responses to polysaccharide vaccines for at least 6 months. ^[3]
• Splenectomy: long-term treatment-free remission in a majority. Reported initial overall response rates up to 90% and 60% to 78% maintaining remission at 10 years (values from the international consensus report; Stasi 2011 reports initial complete response 60% to 70% and long-term 60% to 70%). ^[3] Delay at least 12 months (ideally 12 to 24) after diagnosis because of the chance of spontaneous remission. ^[2][3] Requires pneumococcal, meningococcal and Haemophilus influenzae vaccination at least 2 weeks beforehand (and not within 6 months of rituximab if possible), laparoscopic approach where available, and postsplenectomy sepsis prophylaxis counselling with antibiotic access for fever. ^[2][3] Do not perform before 5 years of age for children. ^[2]
• Other agents for those failing standard therapy: fostamatinib (SYK inhibitor), mycophenolate mofetil, dapsone, danazol, azathioprine, cyclosporine A, vinca alkaloids (not as chronic therapy because of neuropathy) and, in emergencies, vincristine or vinblastine. ^[3] The 2026 update suggests a BTK inhibitor, mycophenolate or a SYK inhibitor for adults who are ineligible for or decline TPO-RAs and rituximab, and it does not consider azathioprine equivalent (less favourable benefit-to-harm ratio, though useful for low cost, global availability and pregnancy safety). ^[4]

When patients remain at bleeding risk after failing multiple therapies (usually at least a TPO-RA and rituximab, and often splenectomy), reconsider the diagnosis, perform a bone marrow examination if not done, reassess the need and adequacy of treatment, and refer to a specialised ITP centre. ^[3]

Life-threatening bleeding (including intracranial haemorrhage) at any platelet count, or major mucosal bleeding with counts under 20 × 10^9/L, demands immediate treatment. ^[2][3]

• Combine IV corticosteroids (methylprednisolone 1 g daily for 3 days is a common regimen), IVIG (1 g/kg, repeated the next day if the count stays under 50 × 10^9/L), and platelet transfusion. ^[1][3]
• Add IV anti-D where suitable; consider vincristine or vinblastine, and tranexamic acid 15 to 20 mg/kg 8-hourly orally or epsilon-aminocaproic acid 1 to 5 g 4 to 6-hourly (maximum 24 g per day), and TPO-RAs (which take at least 5 days to work). ^[3]
• Emergency splenectomy is a rare last resort; plasmapheresis and recombinant factor VIIa are not recommended. ^[3]
• Platelet transfusion should not be delayed in life-threatening bleeding; transfusion raises the platelet count by more than 20 × 10^9/L in about 42% of bleeding patients. ^[3]
• General measures: stop antiplatelet and anticoagulant drugs where possible, control blood pressure, inhibit menses, minimise trauma; maintain haemoglobin at least 10 g/dL when renal function is impaired, and use desmopressin or oestrogens if needed. ^[3] If anticoagulation is unavoidable (for example atrial fibrillation or metallic valves) it raises the target platelet count for treatment.

The conservative goal in an emergency is simply a haemostatic count rather than a normal one, and the decision to act is clinical rather than platelet-number based.

Most children with newly diagnosed ITP are well and can be managed with observation. ITP in children is usually abrupt and post-infectious, and spontaneous remission within weeks is common. Severe (grade 4) bleeding occurs in 0% to 4% and intracranial haemorrhage in 0% to 1%. ^[2][5]

The ASH 2019 paediatric recommendations, which remain current: ^[2]

• No or minor bleeding: observation rather than corticosteroids or IVIG or anti-D (strong recommendation for IVIG and anti-D).
• Non-life-threatening mucosal bleeding or reduced quality of life: corticosteroids rather than anti-D, and rather than IVIG; or IVIG or anti-D either way. Corticosteroid courses should not exceed 7 days; prednisone 2 to 4 mg/kg/day (maximum 120 mg daily) for 5 to 7 days is preferred over dexamethasone 0.6 mg/kg/day (maximum 40 mg/day) for 4 days. ^[2]
• Outpatient management is suggested even for platelets under 20 × 10^9/L unless there is diagnostic uncertainty, social concern or poor follow-up. ^[2]
• For children failing first-line therapy, TPO-RAs are suggested over rituximab or splenectomy; rituximab over splenectomy. ^[2]
• Splenectomy is rarely indicated in children and should be avoided if possible before 5 years of age or within 1 year of onset. ^[2]

Emergency therapy in children combines IV corticosteroids (methylprednisolone 30 mg/kg/day), IVIG 0.8 to 1 g/kg (often as a single dose, which is effective in 1 to 3 days), optional IV anti-D 75 microg/kg, platelet transfusion (bolus then continuous infusion if bleeding persists), vincristine 0.03 mg/kg and tranexamic acid 15 to 20 mg/kg every 8 hours. ^[2][5] Platelets are transfused in ITP only for life-threatening or grade 3 bleeding. ^[5]

TPO-RAs are licensed for children aged 1 year and older for ITP lasting more than 6 months with an insufficient response to first-line treatment; the lowest effective dose that maintains platelets at or above 50 × 10^9/L should be used. ^[3]

ITP complicates pregnancy at an incidence of about 0.83 per 10 000 pregnant women. ^[3] It is mainly a problem of exclusion because gestational thrombocytopenia and pregnancy-induced hypertension (pre-eclampsia/HELLP) are far more common. A platelet count less than 100 × 10^9/L affects about 1% of women without other causes and less than 80 × 10^9/L affects about 0.1%; a count less than 80 × 10^9/L or a history suggestive of ITP warrants investigation. ^[3]

The maternal platelet count does not predict the fetal platelet count, and treating the mother does not influence neonatal outcome. ^[3]

Practical points: ^[3]

• A stable platelet count of 20 to 30 × 10^9/L is safe during most of pregnancy in a non-bleeding patient; observation is often sufficient, with treatment for bleeding or a planned procedure.
• A count of at least 50 × 10^9/L is preferred for delivery; at least 70 × 10^9/L is needed for neuraxial (epidural or spinal) anaesthesia.
• Initial treatment is oral corticosteroids (prednisone 20 mg daily, adjusted to the minimum) or IVIG, which can raise the count within 1 to 2 days and is preferred when a rapid rise is needed.
• IV anti-D (second and third trimester, RhD-positive non-splenectomised women) appears well tolerated; TPO-RAs may be considered in late pregnancy only when other treatments fail; rituximab for very severe cases; splenectomy if necessary is performed in the second trimester.
• Vinca alkaloids, danazol and teratogenic immunosuppressants should be avoided.

Neonatal management matters because the baby may be thrombocytopenic. Cord platelet counts should be checked at delivery; cranial ultrasound is performed if the count is under 50 × 10^9/L; intracranial haemorrhage, although rare (risk under 1%), is managed with IVIG and limited corticosteroids. ^[3][5] Women who have had a splenectomy are at particular risk of a thrombocytopenic baby. ^[3]

Older adults tolerate thrombocytopenia less well because of greater bleeding, thrombosis and infection risk, and older patients (over 60) respond less well to splenectomy and (with romiplostim) carry a higher thrombosis rate. ^[2][3] In adults, extrasplenic considerations include whether to raise the treatment threshold, and treatment choice may need to account for comorbidity.

When ITP is secondary, treating the cause comes first: antiviral therapy (with monitoring for worsening thrombocytopenia from interferon) for HCV, treatment of HIV before ITP-directed therapy, and eradication of H. pylori in infected patients. ^[2] ITP associated with lupus, antiphospholipid syndrome or lymphoproliferative disease is managed by treating the underlying disease, with ITP therapy as needed.

Outside specialist centres many of the modern options (TPO-RAs, rituximab, avatrombopag, partial splenic embolisation, and even routine H. pylori or HIV testing) are unavailable or unaffordable, and international guidelines cannot simply be applied because they assume resources, drug licensing and follow-up that may not exist. ^[3][5] Practical priorities:

• Isolation of thrombocytopenia must be confirmed with the basic tests (full blood count, film, careful history and examination). A bone marrow examination should be avoided when the picture is typical; it is reserved for atypical features, non-response or rebound after remission. ^[2][3][5]
• Where HIV and HCV are endemic, baseline viral serology should be obtained before any immunoglobulin or immunosuppression. ^[3]
• Treat H. pylori only after testing with a breath or stool antigen test where prevalence justifies it; eradication is recommended when found. ^[3]
• Oral prednisolone is inexpensive and effective initial therapy. IVIG is often scarce and costly; it should be reserved for bleeding, imminent procedures or treatment-resistant cases. Anti-D is not available in many countries, including Europe. ^[1][3]
• Splenectomy remains a valid and cost-effective second line where medicines fail, but should be delayed a year when possible and performed with appropriate antimicrobial prophylaxis and immunisation where these are available. ^[2][3]
• If platelets are needed, transfuse for bleeding rather than for the number. Life-threatening bleeding demands combined therapy as above, including platelet transfusion, IVIG and high-dose corticosteroids. ^[2][3]

• Bleeding: bruising, purpura, mucosal bleeding, and (rarely and predominantly with counts under 20 × 10^9/L) intracranial or gastrointestinal haemorrhage. ^[2]
• Intracranial haemorrhage: 1.4% of adults and 0.1% to 0.4% of children. ^[2]
• Treatment toxicity: corticosteroid-related morbidity (hypertension, diabetes, mood disturbance, osteoporosis), IVIG reactions, haemolysis with anti-D, hepatotoxicity and thrombosis with eltrombopag, and infection risk with rituximab and splenectomy. ^[2][3]
• Thrombosis: paradoxical after TPO-RAs, post-splenectomy portal and splenic vein thrombosis, and any thrombotic event driven by anticoagulation thresholds. ^[3]
• Postsplenectomy sepsis (overwhelming infection with encapsulated organisms), sometimes fatal, is a particular risk in young children. ^[3]
• Evans syndrome and other secondary ITP may present with complications of the underlying disease.

• Children: around 70% to 80% (varies by age and series) remit within weeks to months regardless of treatment; older children, females and those without preceding infection are more likely to develop chronic ITP. ^[1][2] Approximately 10% develop chronic ITP by registry data. ^[2]
• Adults: up to 20% to 45% achieve complete remission by 6 months; identifying later spontaneous remissions is difficult because of treatment use. ^[2] Up to 85% may remit by 5 years, and remission can be induced by therapy (TPO-RAs lead to treatment-free remission in about 15% to 30% of chronic patients and nearly one-third of newly diagnosed patients). ^[3]
• Splenectomy: initial complete response rates 60% to 70%, maintained for many years in 60% to 78%. ^[1]
• Rituximab: 21% maintaining remission at 5 years. ^[3]
• Mortality is mainly in those over 60 and is driven by infection as much as bleeding. ^[1][2]

• ITP is an autoimmune disorder with platelet destruction by IgG (mainly splenic clearance via FcγRIIA and FcγRIIIA) and impaired production from autoantibody effects on megakaryocytes.
• Diagnosis is one of exclusion: isolated thrombocytopenia with normal other cell lines and blood film, plus a normal examination for most patients.
• Primary (no cause found) versus secondary (HIV, hepatitis C, H. pylori, lupus, lymphoproliferative disease, drugs, pregnancy) directs treatment.
• Children tend to have acute onset after infection with spontaneous remission; adults have insidious chronic disease.
• Bleeding risk rises below 20 × 10^9/L; treatment is rarely needed above 20 × 10^9/L without bleeding or other risk factors.
• 2019 ASH: treat adults below 30 × 10^9/L (observation above 30), no more than 6 weeks of corticosteroids (prednisone 0.5 to 2 mg/kg/day or dexamethasone 40 mg/day for 4 days), IVIG 1 g/kg on 1 to 2 days, anti-D 50 to 75 microg/kg once when available, TPO-RAs, rituximab and delayed splenectomy for second line.
• 2026 ASH update (adults, primary ITP): add rituximab or a TPO-RA to corticosteroids initially, and favour a TPO-RA (recommended) or rituximab (conditional) second line, with BTK inhibitors, mycophenolate or SYK inhibitors as additional options.
• Emergencies use IV corticosteroids plus IVIG plus platelet transfusion, without delaying transfusion in life-threatening bleeding, plus tranexamic acid and (in children) anti-D.
• Pregnancy: observe to 20 to 30 × 10^9/L, aim for at least 50 × 10^9/L and at least 70 × 10^9/L for neuraxial anaesthesia; treat with corticosteroids or IVIG.
• Paediatric watch-and-wait is the default; transfuse platelets in ITP only for life-threatening or grade 3 bleeding.
• Check HIV, hepatitis C and (in relevant geography) H. pylori; no routine bone marrow in typical ITP.

• Haematology: haemostasis and platelet production
• Haematology: thrombocytopenia as a presentation
• Haematology: thrombotic thrombocytopenic purpura and haemolytic-uraemic syndrome
• Haematology: Evans syndrome
• Haematology: splenectomy
• Pharmacology: glucocorticoids
• Pharmacology: rituximab
• Obstetrics: thrombocytopenia in pregnancy
• Infectious disease: HIV, hepatitis C, Helicobacter pylori

(Plain text only: these topics are linked later once their pages are written.)