PLASMIC score

Q: What PLASMIC score suggests TTP?

6–7 points: 62–82 % probability of severe ADAMTS13 deficiency. 5 points is intermediate (5–24 %), 0–4 is low (0–4 %).

Q: Can I use µmol/L for creatinine?

The score is defined in mg/dL. 2.0 mg/dL is about 177 µmol/L (divide µmol/L by 88.4 to get mg/dL).

Q: Does a low PLASMIC score rule out TTP?

It makes severe ADAMTS13 deficiency unlikely, but the score has limited sensitivity and specificity — ADAMTS13 activity remains the diagnostic standard whenever TTP is suspected.

Likelihood of severe ADAMTS13 deficiency (TTP) in thrombotic microangiopathy

Onkopedia TMA (DGHO)

Sources last checked: 2026-10-13

PLASMIC score

Likelihood of severe ADAMTS13 deficiency (TTP) in thrombotic microangiopathy

Platelet count < 30 ×10⁹/L+1Haemolysis: reticulocytes > 2.5 %, or haptoglobin undetectable, or indirect bilirubin > 2 mg/dL+1No active cancer+1No history of solid-organ or stem-cell transplantation+1MCV < 90 fL+1INR < 1.5+1Creatinine < 2.0 mg/dL+1

0–4 — low

Probability of severe ADAMTS13 deficiency 0–4 %.

Use only once microangiopathic haemolytic anaemia with thrombocytopenia is established. A bridge until ADAMTS13 activity is available — not a diagnosis of TTP.

Source: 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.Open

Interpretation

0–4 — low	Probability of severe ADAMTS13 deficiency 0–4 %.
5 — intermediate	Probability 5–24 %.
6–7 — high	Probability 62–82 %; TTP is likely — a haematological emergency. Confirmation rests on ADAMTS13 activity, for which the score is designed as a bridge.

What is the PLASMIC score?

The PLASMIC score estimates the probability of severe ADAMTS13 deficiency — the hallmark of thrombotic thrombocytopenic purpura (TTP) — in adults with thrombotic microangiopathy. It awards one point each for platelets < 30 ×10⁹/L, haemolysis, no active cancer, no transplant, MCV < 90 fL, INR < 1.5 and creatinine < 2.0 mg/dL. It was derived and externally validated by Bendapudi and colleagues in 2017 in the Harvard TMA registry.

When to use it

In adults with microangiopathic haemolytic anaemia and thrombocytopenia while ADAMTS13 activity is pending
As an early estimate of TTP likelihood while plasma exchange and immunotherapy for suspected immune TTP are being discussed
Where ADAMTS13 testing is slow or unavailable

When not to use it

Before microangiopathic haemolysis with thrombocytopenia has been established
As a replacement for ADAMTS13 testing, which remains the diagnostic standard
In children, where it has not been validated

How it is calculated

Criterion	Points
Platelet count < 30 ×10⁹/L	+1
Haemolysis: reticulocytes > 2.5 %, or haptoglobin undetectable, or indirect bilirubin > 2 mg/dL	+1
No active cancer	+1
No history of solid-organ or stem-cell transplantation	+1
MCV < 90 fL	+1
INR < 1.5	+1
Creatinine < 2.0 mg/dL	+1

Clinical pearls and limitations

Use only once microangiopathic haemolytic anaemia with thrombocytopenia is established. A bridge until ADAMTS13 activity is available — not a diagnosis of TTP.
Creatinine < 2.0 mg/dL (≈ 177 µmol/L) favours TTP; marked renal failure points to HUS.
INR < 1.5 helps separate TTP from DIC; MCV < 90 fL helps exclude B12/folate deficiency and MDS.
The French TMA score is an alternative with fewer items.

Frequently asked questions

What PLASMIC score suggests TTP?

6–7 points: 62–82 % probability of severe ADAMTS13 deficiency. 5 points is intermediate (5–24 %), 0–4 is low (0–4 %).

Can I use µmol/L for creatinine?

The score is defined in mg/dL. 2.0 mg/dL is about 177 µmol/L (divide µmol/L by 88.4 to get mg/dL).

Does a low PLASMIC score rule out TTP?

It makes severe ADAMTS13 deficiency unlikely, but the score has limited sensitivity and specificity — ADAMTS13 activity remains the diagnostic standard whenever TTP is suspected.

Evidence and guidelines

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