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ukmla 2026

Immune Thrombocytopenia (ITP)

Autoimmune destruction of platelets by antiplatelet antibodies — isolated thrombocytopenia with petechiae/purpura, normal marrow megakaryocytes, and exclusion diagnosis

Review date
reviewed 2026-04-05
Reading time
5 min read
Author
Dr Kola Tytler MBBS CertHE MBA MSt MRCGP
Haematology & Oncologyless-commonacute-on-chronic
On this page
Condition details
Haematology & Oncology
less-common
5 min read
reviewed 2026-04-05
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About This Page

This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.

Key points

  • Isolated thrombocytopenia (low platelets, normal Hb, normal WCC, normal coagulation) caused by autoimmune platelet destruction — a diagnosis of EXCLUSION
  • Children: often acute, self-limiting, post-viral. Adults: often chronic and relapsing
  • No diagnostic test — ITP is diagnosed by excluding other causes of thrombocytopenia. Bone marrow biopsy not routinely required
  • Treatment only if platelets <30 × 10⁹/L or significant bleeding. First-line: prednisolone 1 mg/kg or IVIG (if rapid response needed)
  • Second-line: rituximab, TPO receptor agonists (eltrombopag, romiplostim), or splenectomy

Overview

Immune thrombocytopenia (ITP) is an autoimmune disorder characterised by isolated thrombocytopenia (platelet count <100 × 10⁹/L) due to immune-mediated platelet destruction and impaired platelet production. Autoantibodies (usually IgG against platelet surface glycoproteins GPIIb/IIIa or GPIb/IX) opsonise platelets for splenic destruction. The diagnosis is one of exclusion — there is no single confirmatory test. ITP is classified as primary (no identifiable cause) or secondary (associated with SLE, CLL, hepatitis C, HIV, H. pylori).

Epidemiology

ITP has an incidence of approximately 3-4 per 100,000 adults per year. In children, the peak incidence is age 2-6 years and is often post-viral and self-limiting (80% resolve within 6 months). In adults, it is more common in women (3:1) and tends to be chronic. Secondary ITP should always be considered — check for SLE, HIV, hepatitis C, CLL, and drug-induced causes (heparin, quinine).

Clinical Features

Symptoms
Petechiae — non-blanching pinpoint spots, often on dependent areas and mucous membranes
Easy bruising (ecchymoses) — often disproportionate to trauma
Mucosal bleeding: epistaxis, gum bleeding, menorrhagia
May be asymptomatic even with low platelets
Intracranial haemorrhage (very rare but life-threatening — usually platelets <10 × 10⁹/L)
Signs
Petechiae and purpura
Bruising
Wet purpura (blood blisters in mouth) — suggests more severe disease
NO splenomegaly (if spleen is enlarged, consider other diagnoses — CLL, lymphoma, liver disease)
NO lymphadenopathy or hepatomegaly

Investigations

First-line
FBCISOLATED thrombocytopenia: low platelets with normal Hb and WCC. This is the key feature — if other cell lines are abnormal, consider alternative diagnoses
Blood filmReduced platelets, large platelets (megathrombocytes — young platelets from increased production). No fragmented red cells (excludes TTP/HUS). No blasts
Coagulation screen (PT, APTT, fibrinogen)NORMAL in ITP — if abnormal, consider DIC, TTP, or liver disease
Second-line
HIV, Hepatitis B/C serologyExclude viral causes of secondary ITP
Autoimmune screen (ANA, dsDNA)Exclude SLE-associated ITP
H. pylori testingTest and treat if positive — H. pylori eradication can improve platelet count in secondary ITP
Thyroid function testsAutoimmune thyroid disease association
Immunoglobulins and protein electrophoresisExclude CLL or lymphoproliferative disorder in older patients
Specialist
Bone marrow biopsyNOT routinely required (clinical diagnosis). Indicated if: age >60 (exclude MDS), atypical features, failure to respond to treatment, or pre-splenectomy
Antiplatelet antibodiesNOT recommended routinely — low sensitivity and specificity. ITP remains a clinical exclusion diagnosis

Management

BSH Guidelines on ITP (2019, updated 2023)
1
When to treat
  • Platelets >30 × 10⁹/L and no bleeding: OBSERVATION — no treatment needed
  • Platelets <30 × 10⁹/L or significant mucocutaneous bleeding: initiate treatment
  • Severe bleeding at any platelet count: emergency treatment
2
First-line treatment
  • Prednisolone 1 mg/kg/day for 1-2 weeks then taper over 4-6 weeks — response in ~80% but relapse is common
  • Dexamethasone 40 mg daily for 4 days (pulse therapy): alternative to prolonged prednisolone
  • IV immunoglobulin (IVIG) 1 g/kg: for rapid platelet rise when urgent (pre-surgery, active bleeding, or steroids contraindicated). Response within 24-48 hours but transient
3
Second-line treatment (persistent or chronic ITP)
  • Rituximab (anti-CD20): ~60% response rate, durable in ~30%
  • TPO receptor agonists: eltrombopag (oral) or romiplostim (SC injection weekly) — stimulate platelet production, effective in >80%, ongoing treatment usually required
  • Splenectomy: historically second-line, now often deferred in favour of medical therapy. ~65% long-term response. Ensure vaccination (pneumococcal, Hib, meningococcal) ≥2 weeks before
4
Emergency management (life-threatening bleeding)
  • Platelet transfusion (even though consumed rapidly — provides temporary haemostasis)
  • IV methylprednisolone 1g daily for 3 days
  • IVIG 1g/kg
  • Tranexamic acid as adjunct
  • Consider emergency splenectomy if medical treatment fails

Complications

  • Intracranial haemorrhage: The most feared complication — rare (<1%) but potentially fatal, usually with platelets <10 × 10⁹/L
  • Treatment side effects: Long-term steroids (osteoporosis, diabetes, infection), splenectomy (infection risk — encapsulated organisms)
  • Chronic/refractory ITP: ~30% of adults develop chronic ITP requiring ongoing management
UKMLA Exam Tips
  • 1ITP = ISOLATED thrombocytopenia. If Hb low or WCC abnormal = it's NOT ITP (think MDS, leukaemia, aplastic anaemia)
  • 2NO splenomegaly in ITP — if the spleen is palpable, reconsider the diagnosis
  • 3Do NOT routinely check antiplatelet antibodies — they are unreliable and NOT recommended by BSH
  • 4Children post-viral: usually self-limiting. Adults: usually chronic
  • 5Platelets >30 and no bleeding = NO TREATMENT. Don't treat the number, treat the patient
  • 6IVIG for rapid rise (pre-procedure, active bleeding). Steroids for sustained response
  • 7Wet purpura (mucosal blood blisters) = higher risk of serious bleeding — treat more urgently

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Verified Sources & References

BSH Guidelines — Immune Thrombocytopenia (2019, updated 2023)
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