PLASMIC score for thrombotic thrombocytopenic purpura
Seven bedside criteria that estimate the probability of severe ADAMTS13 deficiency in thrombotic microangiopathy.
Switch how results are explained
Low probability of severe ADAMTS13 deficiency (PLASMIC 0-4). TTP is unlikely; look for another cause of the thrombotic microangiopathy.
- Evidence grade
- B
What it is and when to use it
PLASMIC gives one point for each of seven criteria: platelets < 30 ×10⁹/L; haemolysis (reticulocytes > 2.5%, undetectable haptoglobin or indirect bilirubin > 2 mg/dL); no active cancer in the past year; no solid-organ or stem-cell transplant; MCV < 90 fL; INR < 1.5; and creatinine < 2.0 mg/dL. The total ranges from 0 to 7.
How to interpret it
0–4 low, 5 intermediate and 6–7 high probability of severe ADAMTS13 deficiency (activity ≤ 10%). A high score supports starting plasma exchange while the ADAMTS13 result is pending; a low score points to another cause of thrombotic microangiopathy.
Limitations and when not to use it
Use it only in adults with thrombotic microangiopathy (microangiopathic haemolytic anaemia with thrombocytopenia). It estimates pretest probability and does not replace ADAMTS13 activity testing, which should be drawn before plasma is given. Treatment decisions are made with haematology.
Formulas and cut-offs are from the original authors of each score; see the references.
Last reviewed: June 2026
References
- Bendapudi PK, Hurwitz S, Fry A, et al. Derivation and external validation of the PLASMIC score for rapid assessment of adults with thrombotic microangiopathies: a cohort study. Lancet Haematol. 2017;4(4):e157-e164. PMID:28259520