Conditions · Hematology and oncology
Immune thrombocytopenia (ITP) !
ITP is an autoimmune disease in which antibodies destroy platelets, causing easy bruising and pinpoint bleeding under the skin.
Updated 2026-11-01
Structures involved
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In the clinical exam
Why it happens
- Hemorrhage: petechiae, purpura, ecchymosis, hematoma, and what blood loss does
- Primary hemostasis and platelets
- Innate and adaptive immunity: overview
- Lymph node and spleen under the microscope
What it is
An acquired autoimmune disorder with an isolated low platelet count (below 100,000/µL) caused by antibody-mediated platelet destruction and reduced platelet production, after other causes have been excluded. It ranges from a self-limited illness in children to a chronic disease in adults.
Who gets it
In children it often follows a viral infection or vaccination and usually resolves within months. In adults it is more often chronic and more common in women of childbearing age, with a second rise in older people. In the tropics, including Colombia, dengue is a frequent cause of acute thrombocytopenia that must be distinguished from ITP.
Causes
- Primary: autoantibodies against platelet glycoproteins (mainly GPIIb/IIIa) with no other cause
- Secondary to infection: HIV, hepatitis C, Helicobacter pylori, recent viral illness
- Secondary to autoimmune disease: systemic lupus erythematosus, antiphospholipid syndrome
- Secondary to lymphoproliferative disease such as chronic lymphocytic leukaemia
- Some drugs (drug-induced immune thrombocytopenia is classified separately)
Risk factors
- Recent viral infection in children
- Female sex in young and middle-aged adults
- Other autoimmune diseases
- HIV, hepatitis C and H. pylori infection
Pathophysiology
IgG autoantibodies coat platelets, which are then removed by macrophages, mainly in the spleen. Cytotoxic T cells also attack platelets, and antibodies impair megakaryocytes, so production does not rise enough to compensate. The marrow shows normal or increased megakaryocytes, and the spleen is not enlarged.
Classification
- Newly diagnosed: up to 3 months
- Persistent: 3 to 12 months
- Chronic: more than 12 months
- Primary or secondary
Symptoms and signs
- Often no symptoms; found on a routine blood count
- Petechiae and purpura, especially on the legs
- Easy bruising
- Gum bleeding, nosebleeds and blood blisters in the mouth (wet purpura)
- Heavy menstrual bleeding
- Normal-sized spleen and otherwise well appearance
Diagnosis
- Clinical
- A diagnosis of exclusion: a well person with mucocutaneous bleeding, no splenomegaly or lymphadenopathy, and no drug or illness that explains the low platelets.
- Tests
- Complete blood count with isolated thrombocytopenia and a peripheral smear (to exclude clumping, schistocytes and blasts; platelets may be large). Testing for HIV, hepatitis C and often H. pylori; in selected cases antinuclear antibodies, thyroid tests and immunoglobulins. Bone marrow examination is reserved for atypical features, age over 60 or failure to respond.
- Imaging
- Not needed routinely; ultrasound if splenomegaly or liver disease is suspected. Head CT if intracranial bleeding is suspected.
Differential diagnosis
- Pseudothrombocytopenia from platelet clumping in the tube
- Dengue and other viral infections
- Acute leukaemia, aplastic anaemia and myelodysplasia
- Thrombotic thrombocytopenic purpura, haemolytic uraemic syndrome and DIC
- Drug-induced and heparin-induced thrombocytopenia
- Hypersplenism in cirrhosis; gestational thrombocytopenia in pregnancy
Goal of treatment
Prevent serious bleeding rather than normalise the platelet count; treatment is based on bleeding and risk, not on the number alone.
Treatment
- Follow-up
- Observation without drug treatment for most children and for adults with mild thrombocytopenia and no significant bleeding.
- Medical
- Corticosteroids are first line when treatment is needed; intravenous immunoglobulin (or anti-D in selected Rh-positive patients) when a rapid rise is required.
- Medical
- Second line for persistent or chronic disease: thrombopoietin receptor agonists, rituximab and other immunosuppressants; H. pylori eradication when the infection is present.
- Surgical
- Splenectomy for selected adults with chronic ITP who do not respond, with vaccination against encapsulated bacteria beforehand.
- Acute
- Life-threatening bleeding: platelet transfusion together with intravenous immunoglobulin and high-intensity corticosteroids.
- Lifestyle
- Bleeding precautions: avoid aspirin and NSAIDs, contact sports and intramuscular injections; use a soft toothbrush.
Drugs for this condition
Complications
- Intracranial haemorrhage (rare but the most feared)
- Gastrointestinal or heavy menstrual bleeding
- Adverse effects of long-term corticosteroids
- Overwhelming infection after splenectomy
- Neonatal thrombocytopenia in babies of mothers with ITP
Prognosis
Most children recover spontaneously within 6 to 12 months. In adults the disease is chronic in most cases, but serious bleeding is uncommon and most patients live normally with or without treatment.
Test yourself
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What is the typical presentation of ITP in a child?
A well child with sudden petechiae and bruising a few weeks after a viral infection, with isolated thrombocytopenia and no splenomegaly.
Against which platelet antigen are ITP autoantibodies most often directed?
Glycoprotein IIb/IIIa.
What is the usual first-line drug treatment of ITP that needs therapy?
Corticosteroids, with intravenous immunoglobulin when a rapid platelet rise is needed.
Which drugs should be avoided in a patient with ITP?
Aspirin and NSAIDs, because they further impair platelet function and raise bleeding risk.
Which finding argues against ITP and calls for more testing?
Splenomegaly, lymphadenopathy, fever or abnormalities in other cell lines, such as anaemia with blasts.
Related conditions
- Systemic lupus erythematosus
- HIV infection and AIDS
- Helicobacter pylori gastritis
- Dengue
- Disseminated intravascular coagulation
- Acute leukaemia (AML and ALL)
- Intracerebral haemorrhage
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Immune thrombocytopenic purpura (ITP) (MedlinePlus (U.S. National Library of Medicine), 2026).
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