Haematology & Oncology

Immune Thrombocytopenia (ITP)

Immune thrombocytopenia is an acquired immune-mediated platelet disorder causing isolated thrombocytopenia and a mucocutaneous bleeding phenotype; diagnosis is one of exclusion, and treatment is guided by bleeding risk, platelet count, comorbidity and treatment burden rather than the count alone.

In a nutshell

ITP is an acquired immune-mediated isolated thrombocytopenia causing mucocutaneous bleeding. Exclude pseudothrombocytopenia, drug effects, TTP, marrow disease and secondary causes. Observe selected low-risk patients; use a short corticosteroid course when treatment is needed, intravenous immunoglobulin for a rapid rise, and specialist second-line therapy for persistent or chronic disease.

Classic presentation

An otherwise well patient with petechiae, bruising or mucosal bleeding has an isolated low platelet count and no blasts, schistocytes, other cytopenias, splenomegaly or systemic illness.

Key points

ITP is a diagnosis of exclusion; repeat the count and inspect the blood film before committing to the label.
Bleeding phenotype and clinical context matter more than a platelet count viewed in isolation.
Neurology, renal injury, haemolysis or schistocytes should trigger an urgent TTP or thrombotic-microangiopathy pathway.
Major bleeding needs urgent combined haematology treatment; platelet transfusion is rescue therapy, not routine prophylaxis.
NICE technology appraisals define restricted adult pathways for romiplostim, eltrombopag and fostamatinib; they are not interchangeable with first-line treatment.
Children, pregnancy, procedures and antithrombotic therapy need age- and situation-specific specialist planning.

First-line investigation

Repeat full blood count with blood film, exclude pseudothrombocytopenia, and use targeted history, examination and investigations to exclude secondary ITP and dangerous mimics.

Management

Recognise bleeding that cannot wait

For intracranial, gastrointestinal, pulmonary, retinal or other critical-site bleeding, haemodynamic instability or rapidly progressive bleeding, involve senior haematology, transfusion and critical-care teams immediately and activate the local major-haemorrhage pathway when indicated.^6,1,2
Give intravenous corticosteroid and intravenous immunoglobulin for serious or life-threatening bleeding; add platelet transfusion as specialist rescue therapy rather than waiting for the count to recover.^6,1,2,7

Confirm the pattern and exclude dangerous mimics

Repeat the full blood count and review the film, exclude pseudothrombocytopenia, and check for other cytopenias, blasts, clumping or schistocytes before calling the thrombocytopenia ITP.^1,2,5
If thrombocytopenia is accompanied by microangiopathic haemolysis, neurological or renal features, send urgent specialist tests including ADAMTS13 and treat the presentation as possible TTP or TMA until excluded.⁵

Observe or treat according to bleeding risk

Observe many children and selected low-risk adults who have no significant bleeding. NICE's committee discussion describes watch-and-rescue as an option for some lower-risk adults with platelets above 30 x 10^9/L, but the final decision must include age, comorbidity, antithrombotic therapy and procedural risk.^3,1,2
When treatment is indicated, use a short corticosteroid course directed by haematology; use intravenous immunoglobulin when a rapid rise is required for bleeding or an urgent procedure, following the current BNF and local protocol.^1,2,7

Use restricted second-line options deliberately

For selected adults with chronic ITP after standard active and rescue treatments, NICE recommends eltrombopag or romiplostim when the disease remains severe or the person needs frequent rescue; discuss thrombosis, liver, interaction and monitoring issues with the specialist team.^8,9,11,7
For refractory chronic adult ITP, NICE recommends fostamatinib after a thrombopoietin-receptor agonist or when one is unsuitable, subject to the NICE commercial arrangement. Rituximab, mycophenolate and splenectomy remain individualised specialist decisions.^10,1,2,7

Make the long-term plan explicit

Arrange haematology follow-up with a written bleeding and rescue plan, review platelet trends and bleeding rather than a single number, and monitor menstrual bleeding, iron deficiency, fatigue, infection risk, steroid toxicity, splenectomy vaccination and treatment-related thrombosis.^2,11,10,7
Plan pregnancy, delivery, neuraxial anaesthesia, surgery and dental procedures with obstetric, anaesthetic, surgical and haematology teams; do not apply a generic platelet threshold without a situation-specific specialist plan.^1,2,5

Exam traps

Do not diagnose ITP from a low automated platelet count without excluding EDTA-dependent platelet clumping.
Schistocytes with haemolysis, neurological features or renal injury point toward TTP or another thrombotic microangiopathy, not uncomplicated ITP.
Platelet transfusion is not routine in ITP because the transfused platelets are also cleared; reserve it for serious bleeding or an urgent specialist indication.
NICE TAs for thrombopoietin-receptor agonists and fostamatinib describe selected chronic or refractory adult pathways, not routine newly diagnosed disease.
Do not stop clinically necessary anticoagulation or antiplatelet treatment without senior and haematology review.

Illustrations

Petechiae and purpura of the lower leg in ITPA clinical photograph showing widespread petechiae and small purpuric lesions across the lower leg in severe immune thrombocytopenia.James Heilman, MD, Wikimedia Commons · CC-BY-SA-4.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.