Table 1.
Findings in Immune-Mediated Thrombocytopenia
| PTP | ITP | DITP | TTP | HIT | |
|---|---|---|---|---|---|
| Symptoms Onset | 5–10 days after transfusion | -Infection -Altered Immune homeostasis (e.g. Lymphoma) |
7−14 days after starting medication | Idiopathic onset | 5–10 days after heparin exposure |
| Thrombocytopenia | -Severe <10,000/µL |
-Variable | -Variable | -Severe -Median-10,000/µL65 |
-Median nadir-50–60,000/µL -50% reduction in PLT count29,66–68 |
| Bleeding Characteristics | -Bleeding can be severe | -Variable severity | -Variable severity -Can have extensive purpura and GI bleeds -Can present with MAHA in quinine- associated disease69 |
-Petechiae, bruising, hematuria seen in ~60% of patients70 -Microvascular thrombosis |
-Bleeding is uncommon -High risk of thrombosis -Venous> arterial thrombi |
| Platelet Antibody Testing | -HPA-specific antibodies with possible HLA antibodies present -Indirect testing can be performed |
-Pan reactive autoantibodies -Direct Testing can be performed |
-Reactivity with normal platelets in the presence of the offending drug | -Negative reactivity unless previously immunized | Positive Heparin/PF4-antibody testing |
| Other Diagnostic Tools | -HPA genotyping | -Coagulation studies -PBS w/large platelets |
-Drug history | -ADAMTS13 activity/inhibitor -PLASMIC scoring71,72 -PBS w/schistocytes |
-4T scoring73,74 -Serotonin release assay |
| Treatments | -IVIG -Steroids -PLEX7,55–57 |
-Steroids -IVIG -Anti-D immune globulin -Splenectomy -Rituximab75 TPO-RA76 |
-Drug cessation -Transfusion for bleeding/very low PLT count -Steroids69 |
-PLEX -Adjunct therapy w/Caplacizumab77 or Rituximab7 |
-Heparin cessation -Non-heparin anticoagulant78 |
Note: These are typical findings in various immune thrombocytopenia syndromes.
Abbreviations: PLT, platelet; PTP, post transfusion purpura; ITP, immune thrombocytopenic purpura; DITP, drug-induced thrombocytopenia; MAHA, microangiopathic hemolytic anemia; H/PF-4, heparin/platelet factor 4; HPA, human platelet antigen; HLA, human leukocyte antigen; PBS, peripheral blood smear; IVIG, intravenous immunoglobulin, PLEX, plasma exchange; TPO-RA, thrombopoietin receptor agonists.