MDCalc

PLASMIC Score for TTP

Predicts ADAMTS13 deficiency in suspected thrombotic thrombocytopenic purpura (TTP) with high discrimination.

Use in hospitalized adult inpatients with suspected thrombotic thrombocytopenic purpura (TTP) who might benefit from early initiation of plasma exchange while awaiting ADAMTS-13 results. Do not use in patients who have already undergone plasma exchange (i.e., intermediate and high risk groups, in whom therapeutic plasma exchange must be initiated immediately).

Platelet count <30 x 109/L
Hemolysis
Reticulocyte count >2.5%, haptoglobin undetectable, or indirect bilirubin >2.0 mg/dL (34.2 µmol/L)
Active cancer
Treated for cancer within the past year
History of solid-organ or stem-cell transplant
MCV <9.0 x 10-14 L (<90 fL)
INR <1.5
Creatinine <2.0 mg/dL (176.8 μmol/L)

Result:

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Advice

Low risk (PLASMIC Scores ≤4): consider alternative diagnoses.

Intermediate risk (PLASMIC Score 5): send ADAMTS-13 testing, keep close observation, obtain expert consultation, consider plasma exchange if no other cause identified.

High risk (PLASMIC Scores ≥6): send for ADAMTS-13 testing, obtain expert consultation, immediate plasma exchange.

Management

  • Most hospitals will require patients on plasma exchange to be transferred to a critical care unit for closer observation. 

  • Therapeutic plasma exchange remains the first-line treatment.

  • Plasma transfusion is indicated if plasma exchange cannot be performed immediately. 

  • Red blood cell transfusion can be given to patients with severe bleeding. 

  • Glucocorticosteroids are often given as adjunctive treatment.

  • Management is ideally carried out in consultation with hematology-oncology and transfusion medicine services.

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