Exam

Plasmic Score

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Plasmic Score, ADAMTS13 Enzyme Activity Prediction Tool

  • Indications
  1. Suspected Thrombotic Thrombocytopenic Purpura (TTP)
  • Mechanism
  1. Low ADAMTS13 Enzyme Activity <10% is associated with TTP
  • Criteria
  • Assign one point for each positive criteria
  1. Platelet Count <30,000/uL
  2. Hemolysis (Reticulocyte Count >2.5%, Indirect Bilirubin >2 mg/dl or Haptoglobin undectable)
  3. No active cancer history (treatment in last year)
  4. No Solid Organ Transplant or Stem Cell Transplant history
  5. Mean Corpuscular Volume (MCV) <90 fL
  6. Serum Creatinine <2 mg/dl (<177 uMol/L)
  7. INR <1.5
  • Interpretation
  • Plasmic Score based on total points from criteria above
  1. Score 0 to 4
    1. Low risk (4.3%) of Low ADAMTS13 Enzyme Activity
    2. Consider alternative diagnosis (see Thrombotic Thrombocytopenic Purpura)
  2. Score 5 to 6
    1. Intermediate risk (56.8%) of Low ADAMTS13 Enzyme Activity
    2. Indication to obtain ADAMTS13 testing, obtain expert Consultation and to consider plasma exchange
  3. Score >6
    1. High risk (96%) of Low ADAMTS13 Enzyme Activity
    2. Indication to obtain ADAMTS13 testing, obtain expert Consultation and to begin plasma exchange
  1. Test Sensitivity: 85%
  2. Test Specificity: 89%
  • References
  1. Bendapudi (2014) Blood 124(21): 231 [PubMed]
  2. Bendapudi (2017) Lancet Haematol 4(4): e157-64 [PubMed]
  3. Li (2018) J Thromb Haemost 16(1): 164-9 [PubMed]
  4. Paydary (2020) Transfusion 60(9): 2047-57 [PubMed]