Immune Thrombocytopenic Purpura (ITP)
Definition
Immune Thrombocytopenic Purpura (ITP) — also known as Immune Thrombocytopenia — is an acquired autoimmune disorder characterized by isolated thrombocytopenia (platelet count <100,000/µL)
- It is a diagnosis of exclusion — no other cause of thrombocytopenia should be present.
- Hematologist Referral is must
Classification
|
Type |
Description |
|
Primary ITP |
Isolated thrombocytopenia without identifiable cause. |
|
Secondary ITP |
Occurs secondary to other conditions such as: • SLE, antiphospholipid syndrome • HIV, HCV, CMV, EBV infections • Lymphoproliferative disorders • Drugs (quinine, heparin, sulfa drugs) • Post-vaccination (MMR, COVID-19). |
|
Acute ITP |
Common in children, post-viral, self-limited (<6 months). |
|
Chronic ITP |
Common in adults, insidious, >12 months duration. |
|
Refractory ITP |
includes cases that do not resolve with splenectomy. |
Epidemiology
- Children: 2–4 yrs; post-viral; often acute and self-limiting.
- Adults: 20–50 yrs; more common in women (2–3:1); chronic course.
Pathophysiology
- Autoantibody formation:
- IgG autoantibodies target platelet membrane glycoproteins — usually GPIIb/IIIa or GPIb/IX.
- Produced by autoreactive B cells.
- Impaired megakaryocyte function:
- Antibodies also suppress megakaryocyte maturation → ↓ platelet production.
Clinical Features
1. Bleeding manifestations
- Mucocutaneous bleeding:
- Petechiae, purpura, ecchymoses.
- Gum bleeding, epistaxis, menorrhagia.
- Severe bleeding (rare): GI, GU, intracranial (especially if platelets <20,000/µL).
2. Systemic symptoms
- Usually absent (unlike leukemia or SLE).
- No fever, lymphadenopathy, or hepatosplenomegaly (their presence suggests secondary causes).
3. Children
- Often post-viral (URI, varicella), sudden onset, self-limited within weeks.
Investigations
1. Basic Tests
|
Test |
Findings |
|
CBC |
Isolated thrombocytopenia; Hb and WBC normal. |
|
Peripheral smear |
Normal RBC/WBC morphology; large platelets (young platelets). |
|
Reticulocyte count |
Normal. |
|
OTHER |
Vitamin B12 and folate,Prothrombin time and activated partial thromboplastin time |
Bone marrow examination is not routinely needed, only if atypical features (e.g., pancytopenia, lymph node enlargement, splenomegaly, neutropenia, leukocytosis, atypical lymphocytosis, or anemia in the presence of bone pain, fevers, or unintentional weight loss. , or poor response to therapy).
2. Additional Tests to rule out secondary causes
- HIV, HCV serology (must be done in all adults).
- ANA if SLE suspected.
- TSH, antiphospholipid antibodies, or direct Coombs test in selected cases.
- Individuals with recurrent epigastric pain suggestive of peptic ulcer must be tested for Helicobacter pylori infection, which is a possible cause of ITP.
- No specific diagnostic test for ITP — it’s a diagnosis of exclusion.
Diagnostic Criteria (ASH 2019)
- Isolated thrombocytopenia (<100,000/µL).
- Normal RBC and WBC morphology.
- No other cause of thrombocytopenia identified.
Differential Diagnosis
|
Condition |
Key Difference |
|
Drug-induced thrombocytopenia |
Temporal relation with drug exposure (e.g. quinine, heparin). |
|
SLE/APL syndrome |
Other autoimmune features or antibodies. |
|
Thrombotic microangiopathy (TTP/HUS) |
MAHA, schistocytes, renal/CNS involvement. |
|
Bone marrow failure (AA, leukemia) |
Pancytopenia, hypocellular marrow. |
|
Hypersplenism |
Splenomegaly, sequestration. |
Treatment ITP (Adult) – ASH
1. Treatment Decision (Steroids vs Observation)
|
Platelet Count |
Clinical Status |
Recommendation |
|
< 30,000/µL |
Asymptomatic / minor mucocutaneous bleed |
Corticosteroids |
|
≥ 30,000/µL |
Asymptomatic / minor bleed |
Avoid steroids → Observation |
|
Borderline (~30k) |
Any |
Individualize |
Override factors (favor steroids even if ≥30k)
- Age > 60 years
- Anticoagulant / antiplatelet use
- Planned surgery/procedure
- Significant comorbidities
- Platelets trending down
2. Admission vs Outpatient Management
|
Platelet Count |
ITP Status |
Clinical Status |
Recommendation |
|
< 20,000/µL |
Newly diagnosed |
Asymptomatic / minor bleed |
Admit |
|
< 20,000/µL |
Established ITP |
Asymptomatic / minor bleed |
Outpatient |
|
≥ 20,000/µL |
Any |
Asymptomatic / minor bleed |
Outpatient |
3. When to Consider Admission (Even if ≥20k)
|
Situation |
Reason |
|
Diagnostic uncertainty |
Could be other serious cause |
|
Social issues |
Poor follow-up / access |
|
High bleeding risk |
Comorbidities |
|
Clinical concern |
Physician judgment |
First-line Therapy
|
Treatment |
Dose |
Comments |
|
Corticosteroids |
Prednisolone 1 mg/kg/day × 2–4 weeks, then taper OR Dexamethasone 40 mg/day × 4 days (repeat every 2–4 weeks × up to 3 cycles). |
Rapid response in 2–5 days. Avoid long-term steroids. |
|
IV Immunoglobulin (IVIg) |
1 g/kg/day × 1–2 days |
For rapid rise (e.g., severe bleeding, pre-op, pregnancy). |
|
Anti-D Immunoglobulin (Rh⁺, non-splenectomized only) |
50–75 µg/kg IV once |
Causes mild hemolysis; used less now. |
Second-line Therapy (for steroid failure or relapse)
|
Option |
Mechanism |
Notes |
|
Rituximab |
Anti-CD20 monoclonal antibody |
Response 40–60%; relapse common. |
|
Thrombopoietin receptor agonists (TPO-RAs) |
Stimulate platelet production |
Eltrombopag, Romiplostim; effective in chronic ITP. |
|
Splenectomy |
Removes major site of platelet destruction |
Reserved for chronic, refractory cases; long-term remission in ~60%. |
Refractory ITP Options
- Immunosuppressants: Azathioprine, cyclosporine, mycophenolate, cyclophosphamide.
- Fostamatinib: SYK inhibitor, approved for chronic ITP refractory to ≥2 lines of therapy.
Emergency Management
If life-threatening bleeding (e.g., intracranial, GI, severe epistaxis):
- IV methylprednisolone 1 g/day × 3 days
- IVIg 1 g/kg/day which may be repeated the next day if the platelet count remains below 50,000/μL.
- Platelet transfusion ( apheresis unit or 4 to 6 pooled platelet units. )
- Maintain hemodynamic stability and local hemostasis.
ITP in Pregnancy
- Similar pathogenesis.
- Treat if platelet <30,000 or bleeding.
- Preferred: Prednisolone ± IVIg.
- Avoid: Rituximab, TPO agonists, splenectomy (except 2nd trimester).
- Delivery: Aim platelet >50,000/µL for vaginal; >80,000/µL for C-section.
Prognosis
- Children: 80–90% recover spontaneously within 6 months.
- Adults: 20–30% have chronic disease.
- Mortality from bleeding <1%, but chronic relapsing course common.
REFERENCE
1.Pietras NM, Gupta N, Justiz Vaillant AA, et al. Immune Thrombocytopenia. [Updated 2024 May 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK562282/
2.ohs intensive care manual