Should I start a short course of low-dose steroids, such as prednisone, to rule out Immune Thrombocytopenic Purpura (ITP) in a patient with giant platelets before evaluating for Bernard-Soulier syndrome?

Management of Giant Platelets: Differentiating ITP from Bernard-Soulier Syndrome

A short course of low-dose steroids is recommended as an initial approach to rule out ITP in a patient with giant platelets before evaluating for Bernard-Soulier Syndrome. 1, 2

Diagnostic Approach for Giant Platelets

When encountering a patient with giant platelets, it's critical to distinguish between acquired causes (like ITP) and inherited disorders (like Bernard-Soulier Syndrome):

1. Initial Steroid Trial:

   • Begin with prednisone 1-2 mg/kg/day for a short course (≤6 weeks including taper)
   • Monitor platelet response after 1 week
   • Response to steroids strongly suggests ITP 1

2. Response Interpretation:

   • Positive response (platelet count increase): Supports ITP diagnosis
   • No response: Consider Bernard-Soulier Syndrome or other inherited thrombocytopenias 3, 4

Why This Approach Works

Bernard-Soulier Syndrome (BSS) is frequently misdiagnosed as ITP, leading to unnecessary treatments 3. The key differences:

• ITP: Acquired autoimmune disorder with:

  • Response to steroid therapy
  • Normal platelet morphology on peripheral smear
  • No family history typically

• Bernard-Soulier Syndrome: Inherited disorder with:

  • No response to steroids, IVIG, or splenectomy
  • Giant platelets on peripheral smear
  • Often has family history
  • Absent response to ristocetin in platelet aggregation studies 4

Steroid Protocol for ITP Trial

The American Society of Hematology recommends:

• Preferred regimen: Short course (≤6 weeks) of prednisone with taper 1
• Initial dose: 1-2 mg/kg/day orally 2
• Duration: 2-4 weeks at full dose, followed by tapering over 4-6 weeks 2
• Alternative: Dexamethasone 40 mg daily for 4 days 2

Evaluation After One Week

After one week of steroid therapy:

• If platelet count improves: Continue steroid taper and manage as ITP
• If no improvement: Discontinue steroids and proceed with specialized testing for Bernard-Soulier Syndrome:
  • Flow cytometry for GPIb expression
  • Platelet aggregation studies (absent response to ristocetin is characteristic of BSS)
  • Genetic testing for mutations in GP1BA, GP1BB, or GP9 genes 3, 4

Common Pitfalls to Avoid

1. Prolonged steroid exposure: Avoid courses >6 weeks as they increase side effects without improving outcomes 1, 2

2. Misdiagnosis: BSS is frequently misdiagnosed as ITP, leading to unnecessary treatments including steroids, IVIG, rituximab, and even splenectomy 3, 4

3. Delayed diagnosis: Patients with BSS may suffer years of inappropriate treatments before correct diagnosis 4

4. Overlooking family history: BSS is autosomal recessive; inquire about consanguinity and family history of bleeding disorders 4

By using a short course of steroids as a diagnostic trial and carefully evaluating the response after one week, you can effectively differentiate between ITP and Bernard-Soulier Syndrome, ensuring appropriate management for your patient with giant platelets.