| Syndrome |
VITT | ITP | TTP |
Thrombocytopenia | - Yes, typically 10,000 to 100,000/microL
| | |
Thrombosis | - Yes, including atypical sites of venous and arterial thrombosis
| - Generally not seen, although there may be a slightly increased risk for VTE
| - Typically microvascular rather than VTE
|
Other clinical | - Temporal relationship to specific COVID-19 vaccines
- Flu-like syndrome
| - Petechiae or purpura
- Often, otherwise well; often an incidental finding
| - Neurologic, kidney, and/or cardiac involvement may be seen
|
Other laboratory | - Normal to slightly prolonged PT and aPTT
- Fibrinogen may be low
- D-dimer often markedly increased
| - Normal PT and aPTT
- Normal fibrinogen and D-dimer
- Normal hemoglobin (unless anemia from bleeding)
| - Normal PT and aPTT
- Normal fibrinogen and D-dimer
- Microangiopathic hemolytic anemia with laboratory findings of hemolysis and schistocytes on the blood smear
|
Diagnostic confirmation | - Positive anti-PF4 antibody ELISA or functional assay
| | - Severe ADAMTS13 deficiency (activity <10%)
|
Management implications* | - Anticoagulation with a non-heparin agent
- Avoid heparin
- Avoid warfarin (unless platelet count has recovered)
- High-dose IVIG
- Minimize platelet and plasma transfusions
| - Platelet transfusions for critical bleeding
- Glucocorticoids or IVIG for serious bleeding or severe thrombocytopenia
- Rituximab, splenectomy, or TPO-RA in selected cases
| - Therapeutic plasma exchange
- Glucocorticoids
- Rituximab
- Caplacizumab in selected cases
- Avoid platelet transfusions unless major bleeding
|