Table 2.
Recommended investigations for suspected immune-related thrombocytopenia.
| Clinical evaluation | |
|---|---|
| Parameter | Points to consider |
| Patient history | Personal history of autoimmune disease (Hashimoto’s thyroiditis, ITP, vitiligo, psoriasis); prior chemo-radiotherapy or lymphocyte-depleting therapy (fludarabine, anti-thymocyte globulin, corticosteroids) |
| Family history | History of autoimmune disease |
| Nutritional evaluation | Iron, folate, vitamin B12 deficiency |
| Physical examination | Splenomegaly, hepatomegaly, purpura, petechiae |
| Standard investigations | |
| Investigation | Points to consider |
| Complete blood count | Other hematological cell lines decreased (coexistence of neutropenia and/or anemia) |
| Peripheral blood smear | Platelet clumping (pseudo-TCP), morphology of platelets (myelodysplastic syndrome) |
| Reticulocyte count | Coexistence of autoimmune hemolytic anemia (Evans syndrome) |
| Direct antiglobulin test [direct Coombs test] | Coexistence of autoimmune hemolytic anemia (Evans Syndrome) |
| Infection panel | HIV, HCV, H. Pylori |
| Bone marrow examination (aspirate/biopsy) | Not always necessary; indicated when other investigations are not conclusive or if other cell lines are affected and there is concern for drug-induced aplastic anemia or bone marrow pathology |
| Optional investigations | |
| Investigation | Points to consider |
| Platelet antibody identification panel/drug-dependent antiplatelet antibodies | Human platelet antibodies HPA-1a/b, HPA-2a/b, HPA-3a/b, HPA-4a, HPA-5a/b, GPIIb/IIIa, GPIa/IIa, GP Ib/IX, GPIV, and class I HLA |
| Anti PF4 | Heparin-induced TCP |
| Additional virus panel | Parvovirus B19, EBV, CMV |
| Coagulation parameters | PT, aPTT, fibrinogen, D-dimers: rule out TMA/TTP/DIC |
| Autoantibody screening | Antinuclear antibodies and antiphospholipid autoantibodies (including lupus anticoagulant and anti-cardiolipin) |
| Antithyroid antibodies and thyroid function | Coexisting autoimmune thyroid disorders (e.g., subclinical hypothyroidism associated with ITP: treating the underlying thyroid disorder may significantly improve platelet count) |
HIV, human immunodeficiency virus; HCV, hepatitis C virus; TCP, thrombocytopenia; HPA, Human platelet antibodies; GP, glycoprotein; HLA, human leukocyte antigen; TMA, thrombotic microangiopathy; TTP, thrombotic thrombocytopenic purpura; DIC, disseminated intravascular coagulation; HIV, human immunodeficiency virus; HCV, hepatitis C virus; HBV, hepatitis B virus; CMV, cytomegalovirus; EBV, Epstein-barr virus; HIT, heparin-induced TCP; ITP, immune thrombocytopenia.