The key diagnostic criteria for immune thrombocytopenia (ITP) in adults include isolated thrombocytopenia with a platelet count typically below 100 x 10⁹/L, in the absence of other causes of thrombocytopenia. Diagnosis is primarily clinical and by exclusion, requiring a thorough history, physical examination, and laboratory tests to rule out secondary causes such as infections, medications, or other hematological disorders NICE CKS.
There is no definitive diagnostic test for ITP; instead, diagnosis relies on:
- Persistent isolated thrombocytopenia without anemia or leukopenia.
- Exclusion of other causes of thrombocytopenia, including bone marrow disorders, liver disease, or systemic illnesses.
- Peripheral blood smear showing reduced platelets but otherwise normal morphology.
- Bone marrow examination is not routinely required but may be considered in atypical cases or if diagnosis is uncertain.
Additional supportive features include the absence of splenomegaly and normal coagulation studies. The presence of bleeding symptoms varies and is not required for diagnosis NICE CKS.
Recent literature emphasizes that ITP remains a diagnosis of exclusion and highlights the importance of ruling out secondary causes and mimics through detailed clinical and laboratory evaluation Lambert & Gernsheimer 2017Neunert et al. 2019Neunert et al. 2024.
Key References
- CKS - Platelets - abnormal counts and cancer
- NG121 - Intrapartum care for women with existing medical conditions or obstetric complications and their babies
- NG24 - Blood transfusion
- CKS - Bruising
- NG17 - Type 1 diabetes in adults: diagnosis and management
- (Lambert and Gernsheimer, 2017): Clinical updates in adult immune thrombocytopenia.
- (Neunert et al., 2019): American Society of Hematology 2019 guidelines for immune thrombocytopenia.
- (Neunert et al., 2024): The 2022 review of the 2019 American Society of Hematology guidelines on immune thrombocytopenia.