II. Indications
- Suspected Thrombotic Thrombocytopenic Purpura (TTP)
III. Mechanism
- Low ADAMTS13 Enzyme Activity <10% is associated with TTP
IV. Criteria: Assign one point for each positive criteria
- Platelet Count <30,000/uL
- Hemolysis (Reticulocyte Count >2.5%, Indirect Bilirubin >2 mg/dl or Haptoglobin undectable)
- No active cancer history (treatment in last year)
- No Solid Organ Transplant or Stem Cell Transplant history
- Mean Corpuscular Volume (MCV) <90 fL
- Serum Creatinine <2 mg/dl (<177 uMol/L)
- INR <1.5
V. Interpretation: Plasmic Score based on total points from criteria above
- Score 0 to 4
- Low risk (4.3%) of Low ADAMTS13 Enzyme Activity
- Consider alternative diagnosis (see Thrombotic Thrombocytopenic Purpura)
- Score 5 to 6
- Intermediate risk (56.8%) of Low ADAMTS13 Enzyme Activity
- Indication to obtain ADAMTS13 testing, obtain expert Consultation and to consider plasma exchange
- Score >6
- High risk (96%) of Low ADAMTS13 Enzyme Activity
- Indication to obtain ADAMTS13 testing, obtain expert Consultation and to begin plasma exchange
VI. Efficacy: Scores >=6 in predicting low ADAMTS13 Enzyme Activity and TTP
- Test Sensitivity: 85%
- Test Specificity: 89%