Immune Thrombocytopenic Purpura (ITP) in Adults
Diagnostic Work-Up
The diagnosis of ITP is primarily clinical, requiring only basic laboratory testing: complete blood count, peripheral blood smear, HIV and HCV testing, with bone marrow examination unnecessary in typical presentations. 1
Essential Diagnostic Steps
Obtain complete blood count and examine peripheral blood smear to confirm isolated thrombocytopenia (platelet count <100 × 10⁹/L) and exclude other cytopenias or abnormal cell morphology 1
Test for HIV and hepatitis C virus in all newly diagnosed patients, as these infections can cause secondary thrombocytopenia 1
Perform additional investigations only if abnormalities exist beyond isolated thrombocytopenia (such as anemia not explained by bleeding, leukopenia, or atypical cells on smear) 1
When Bone Marrow Examination is NOT Needed
Bone marrow examination is unnecessary in patients of any age presenting with typical ITP features (isolated thrombocytopenia, normal or increased megakaryocytes expected, no other cytopenias) 1
Do not perform bone marrow biopsy before initiating corticosteroids or IVIg therapy 1
Critical Pitfall to Avoid
Do not confuse ITP with thrombotic thrombocytopenic purpura (TTP). If the patient has concurrent anemia with schistocytes on smear, elevated LDH, or renal dysfunction, immediately evaluate for TTP with ADAMTS13 testing, as TTP requires urgent plasma exchange rather than ITP-directed therapy. 2
First-Line Treatment
For adults with newly diagnosed ITP requiring treatment, use a short course (≤6 weeks) of corticosteroids, specifically prednisone 1 mg/kg daily for 21 days then tapered, avoiding prolonged courses beyond 6 weeks. 1
When to Treat vs. Observe
Treat patients with platelet counts <20-30 × 10⁹/L who have mucosal bleeding (wet purpura, epistaxis, gingival bleeding, menorrhagia) or significant bleeding risk factors (hypertension, anticoagulation need, high-risk activities) 1
Observe without treatment patients with platelet counts >30 × 10⁹/L who have only skin manifestations (dry purpura, petechiae, bruising) and no bleeding 1
Consider treatment for platelet counts 20-30 × 10⁹/L based on bleeding severity, comorbidities (age >60, hypertension), and patient activity level 1
Specific First-Line Regimens
Option 1: Prednisone (Preferred by ASH 2011)
- Prednisone 1 mg/kg orally daily for 21 days, then taper over the subsequent weeks provides longer duration of response compared to short-course dexamethasone 1
- Initial response rate: 70-80% 3
- Strongly avoid prolonged courses exceeding 6 weeks (including taper) due to cumulative corticosteroid toxicity without additional benefit 1, 3
Option 2: High-Dose Dexamethasone
- Dexamethasone 40 mg orally daily for 4 days offers rapid response (within days) with initial response rate up to 90% 3
- Sustained response rate: 50-80% 3
- Preferred when rapid platelet increase needed or to minimize prolonged corticosteroid exposure 3
Option 3: IVIg (Adjunctive or Alternative)
- IVIg 1 g/kg as single dose can be used when more rapid platelet increase required (e.g., active bleeding, urgent procedure) 1
- Often combined with corticosteroids for faster response 3
- More expensive than corticosteroids; reserve for specific indications 1
Option 4: Anti-D Immunoglobulin
- Can be used in Rh-positive, non-splenectomized patients as alternative first-line therapy 1
- Contraindicated if hemoglobin already decreased from bleeding or evidence of autoimmune hemolysis 1
Critical Pitfall
Never use anti-D immunoglobulin in TTP—it is only indicated for ITP. If diagnostic uncertainty exists between ITP and TTP, do not use anti-D. 2
Second-Line Treatment
For adults with ITP lasting ≥3 months who are corticosteroid-dependent or unresponsive, use thrombopoietin receptor agonists (TPO-RAs) as preferred second-line therapy over rituximab or splenectomy. 1, 3
Treatment Algorithm for Persistent/Chronic ITP (≥3 months)
Step 1: TPO-RA Therapy (Preferred Second-Line)
- Choose either eltrombopag (oral daily) or romiplostim (subcutaneous weekly) based on patient preference for administration route 1, 3
- Both agents equally effective; choice depends on patient preference for daily oral vs. weekly injection 1
- Advantages: Avoid surgery, reversible, effective for bleeding prevention 1
Step 2: Consider Rituximab vs. Splenectomy
- Rituximab preferred over splenectomy for patients who wish to avoid surgery or have surgical contraindications 1
- Splenectomy preferred over rituximab for patients desiring durable response and wishing to avoid long-term medication 1
- TPO-RA preferred over rituximab when comparing these two medical options 1
Step 3: Splenectomy Timing and Preparation
- Delay splenectomy for at least 12 months after diagnosis due to potential for spontaneous remission in first year 1, 3
- Before splenectomy, ensure appropriate immunizations (pneumococcal, meningococcal, Haemophilus influenzae type b) and counsel regarding lifelong antibiotic prophylaxis 1
- Splenectomy indicated for patients with persistent bleeding, lack of response to medical therapies, or quality of life impairment requiring intervention 1
Nuanced Decision-Making for Second-Line Therapy
The 2019 ASH guidelines acknowledge these are conditional recommendations with very low certainty evidence, reflecting that each option (TPO-RA, rituximab, splenectomy) may be appropriate depending on specific patient factors: 1
- Choose TPO-RA for patients requiring ongoing therapy who want to avoid surgery and accept long-term medication
- Choose splenectomy for patients desiring durable remission off medication who accept surgical risks
- Choose rituximab for patients wanting to avoid both surgery and daily/weekly medication, accepting lower durability than splenectomy