Immune thrombocytopenia (ITP)
Autoimmune destruction of platelets causes isolated low platelet count, with bruising, petechiae and bleeding risk. Usually triggered by infection in children (often resolves) or chronic in adults.
What it is
Immune thrombocytopenia is an autoimmune disorder in which IgG autoantibodies bind to platelet surface antigens (mostly GpIIb/IIIa); platelet-antibody complexes are cleared by the spleen and platelet production is also suppressed at the megakaryocyte level. The clinical signature is isolated thrombocytopenia — platelet count low (often <30 × 10⁹/L), while haemoglobin, white-cell count, coagulation studies and blood film are otherwise normal. Children most often develop acute post-viral ITP that resolves within weeks; adults more commonly have chronic ITP that persists >12 months. Drug-induced (heparin, quinine, sulfa) and secondary forms (lupus, HIV, hep C, H. pylori, lymphoproliferative) are important to exclude before labelling primary ITP.
Key lab markers
- Platelets — defining feature; <100 × 10⁹/L for diagnosis, often <30; bleeding risk meaningful <30, surgical bleed risk <50.
- Haemoglobin, WBC — normal unless secondary cause or bleeding.
- Reticulocytes — normal (ITP doesn't affect red-cell turnover).
- Peripheral smear — normal-large platelets, no schistocytes (excludes TTP), no blasts (excludes leukaemia).
- HIV, HCV, H. pylori — screen at first presentation to exclude secondary ITP.
Symptoms
- Easy bruising disproportionate to trauma
- Petechiae (small red-purple spots, especially on shins and oral mucosa)
- Gum bleeding when brushing teeth, prolonged nosebleeds
- Heavier menstrual periods
- Rarely severe: intracranial haemorrhage (platelets <10, with trauma)
When to discuss with a doctor
An incidental low platelet count below 100 × 10⁹/L on a routine CBC, especially in the 10–50 range, needs prompt clinical assessment — examine for petechiae, exclude pseudothrombocytopenia (EDTA clumping), repeat the CBC with citrate tube, and refer to haematology if confirmed. Counts below 30 with any bleeding warrant urgent evaluation. Children often need only observation; adults usually require corticosteroids or IVIG to lift the count. Mediora.AI surfaces the value with bleeding-risk context; ITP diagnosis is one of exclusion done with a haematologist.