The PLASMIC Score for the Diagnosis of Thrombotic Thrombocytopenic Purpura (TTP)
The PLASMIC score assists in the diagnosis and management of thrombotic thrombocytopenic purpura (TTP).
The score accurately distinguishes between thrombocytopenic microangiopathic anemia patients with and without severe ADAMTS13 deficiency: defined as ADAMTS13 activity level ≤10%.
It is used as an adjunct in the diagnosis of TTP, not as a replacement for appropriate clinical judgement.
The name “PLASMIC” refers to the score’s seven components: Platelet count; combined hemoLysis variable; absence of Active cancer; absence of Stem-cell or solid-organ transplant; MCV; INR; Creatinine.
Application of the PLASMIC score should be restricted to patients with a platelet count <150,000 per microliter and schistocytes visible on the peripheral blood smear.
P
Platelet count < 30 x 109/L
No0
Yes+1
L
Combined hemolysis parameter:
Indirect bilirubin > 2mg/dL, OR
Reticulocyte count > 2.5%, OR
Haptoglobin undetectable
No0
Yes+1
A
Patient has active cancer
Defined as treatment for any non-superficial skin cancer within the last 12 months.
No+1
Yes0
S
Patient has a history of solid-organ or stem-cell transplant
No+1
Yes0
M
MCV < 90 fL
No0
Yes+1
I
INR < 1.5
No0
Yes+1
C
Creatinine < 2.0 mg/dL
No0
Yes+1
A PLASMIC score of 6 to 7 indicates a high probability of severe ADAMTS 13 deficiency, whereas a score of five signifies intermediate probability, and scores of 0 to 4 low probability.
Plasma exchange and glucocorticoid therapy recommended for patients with an intermediate to a high probability of iTTP.