This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
Why the PLASMIC score?
Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening disorder. Tiny clots form in small blood vessels, using up platelets and breaking red blood cells. It is caused by a severe deficiency of the enzyme ADAMTS13, usually below 10% activity, most often due to autoantibodies. Untreated, TTP is fatal in most cases, but the ADAMTS13 test can take days. The PLASMIC score, published by Bendapudi and colleagues in Lancet Haematology in 2017, estimates the probability of severe ADAMTS13 deficiency while the result is pending.
The seven items
Each item gives 1 point:
| Item | Point if |
|---|---|
| Platelet count | under 30 × 10⁹/L |
| Hemolysis | reticulocytes over 2.5%, undetectable haptoglobin or indirect bilirubin over 2 mg/dL |
| No active cancer | no cancer treated in the past year |
| No transplant | no solid organ or stem cell transplant |
| MCV | under 90 fL |
| INR | under 1.5 |
| Creatinine | under 2.0 mg/dL |
Interpretation
| Score | Risk | Probability of severe ADAMTS13 deficiency |
|---|---|---|
| 0 to 4 | Low | about 0 to 4% |
| 5 | Intermediate | about 5 to 24% |
| 6 or 7 | High | about 62 to 82% |
A high score supports starting treatment, usually plasma exchange and corticosteroids, often with caplacizumab and rituximab, before ADAMTS13 results come back. A low score points toward other causes of thrombotic microangiopathy, such as hemolytic uremic syndrome, malignant hypertension, cancer or drugs.
Example
A patient has platelets of 18 × 10⁹/L, signs of hemolysis, no cancer, no transplant, an MCV of 85 fL, an INR of 1.1 and a creatinine of 1.2 mg/dL. Every item scores, so PLASMIC is 7: high risk.
Limits
The score was built on adults with thrombotic microangiopathy, defined as low platelets with schistocytes on the blood film. It should not be used to screen every patient with low platelets, and it never replaces the ADAMTS13 test and an urgent hematology opinion.