The Question Contains a Fundamental Error: It Asks About "Idiopathic Thrombocytopenia" When It Should Ask About "Immune Thrombocytopenic Purpura (ITP)"
None of the answer choices (a through e) are correct because they describe diagnostic criteria and treatment for essential thrombocythemia (elevated platelets), not immune thrombocytopenic purpura (low platelets). The question appears to confuse two opposite hematologic conditions.
Correct Diagnostic Criteria for ITP
The diagnosis of ITP requires a platelet count <100 × 10⁹/L (<100,000/mm³), not the elevated counts listed in options a, b, and c. 1
Essential Diagnostic Components
Isolated thrombocytopenia (platelet count <100 × 10⁹/L) is the defining laboratory feature, confirmed by complete blood count. 2, 1
Peripheral blood smear examination must demonstrate normal-sized or slightly larger platelets, normal red blood cell morphology, and normal white blood cell morphology—reviewed by a hematologist or pathologist to exclude pseudothrombocytopenia. 3, 2
ITP is a diagnosis of exclusion; you must rule out other causes through history, physical examination, CBC, and peripheral blood smear. 3, 1
Mandatory Testing in All Adults
HIV antibody testing is required in all adults with suspected ITP, regardless of risk factors, because HIV-associated thrombocytopenia can be clinically indistinguishable from primary ITP and may precede other HIV manifestations by years. 3, 2
Hepatitis C virus testing is mandatory in all adults, as HCV infection may appear years before other symptoms and successful antiviral therapy can lead to complete hematologic remission. 3, 2
Physical Examination Red Flags
Splenomegaly, hepatomegaly, or lymphadenopathy excludes primary ITP and mandates investigation for secondary causes such as HIV, systemic lupus erythematosus, or lymphoproliferative disorders. 4, 3
Physical examination should be normal aside from bleeding manifestations (petechiae, purpura, mucosal bleeding). 3
Why Options d and e Are Incorrect for ITP Treatment
Hydroxyurea and aspirin are NOT treatments for ITP—they are used for essential thrombocythemia (a myeloproliferative disorder with elevated platelets). Using aspirin in ITP would be dangerous because it impairs platelet function and increases bleeding risk in patients who already have critically low platelet counts. 4
Correct First-Line Treatment for ITP
For adults with newly diagnosed ITP requiring treatment, a short course of corticosteroids (≤6 weeks including taper) is recommended over prolonged courses. 4
Intravenous immunoglobulin (IVIg) 0.8–1 g/kg as a single dose is recommended when rapid platelet increase is needed. 4
Treatment is indicated only when:
Second-Line Treatment Options
For ITP lasting ≥3 months who are corticosteroid-dependent or unresponsive, the American Society of Hematology suggests either thrombopoietin receptor agonists (eltrombopag or romiplostim), splenectomy, or rituximab. 4
Splenectomy should be delayed for at least 1 year after diagnosis because of the potential for spontaneous remission in the first year. 4
Critical Diagnostic Pitfalls to Avoid
Never diagnose ITP without personal review of the peripheral blood smear, as automated counters can miss pseudothrombocytopenia (EDTA-dependent platelet clumping), giant platelets suggesting inherited thrombocytopenia, or schistocytes indicating thrombotic microangiopathy. 3, 2
Never skip HIV and HCV testing in adults, even without apparent risk factors, as these infections can masquerade as primary ITP. 3, 2
Do not confuse drug-induced thrombocytopenia with ITP—obtain a detailed medication history including over-the-counter drugs, herbal supplements, and recent heparin exposure. 4, 3
Bone marrow examination is NOT routinely necessary in patients with typical ITP features, but becomes mandatory in patients aged ≥60 years, those with systemic symptoms, abnormal blood count parameters beyond isolated thrombocytopenia, atypical peripheral smear findings, or minimal response to first-line therapies. 3, 2, 1