PLASMIC score for suspected thrombotic microangiopathy (Bendapudi 2017)

The PLASMIC score is a seven-item bedside total for adults with a suspected thrombotic microangiopathy (TMA). Each item scores 1 point, so totals run from 0 to 7, and Bendapudi and colleagues grouped them as 0-4, 5 and 6-7 by the pretest chance of severe ADAMTS13 deficiency. Magent's calculator adds the seven items from the values you supply and returns the total and its group.

Not a medical device. Not a diagnosis or dosing recommendation.

Use this calculator via API

Hematology calculators
Bendapudi PK et al. · 2017
The PLASMIC score table
Worked examples
Frequently asked questions

What is the PLASMIC score?

In a TMA, small clots damage red cells and use up platelets. One cause, thrombotic thrombocytopenic purpura (TTP), comes from severe deficiency of the ADAMTS13 enzyme. The ADAMTS13 test can take time to come back, so Bendapudi's group built a score from information usually available at the start.

The name comes from the items: Platelets, Lysis (hemolysis), Active cancer, Stem-cell or solid-organ transplant, MCV, INR and Creatinine. A higher total puts a person in a group where severe ADAMTS13 deficiency was more common in the derivation and external cohorts.

The score is meant for adults in whom a TMA is already suspected. It isn't a test for TMA itself.

The PLASMIC score table

1 point each:
  platelets below 30 x10^9/L
  hemolysis present
  no active cancer
  no solid-organ or stem-cell transplant
  MCV below 90 fL
  INR below 1.5
  creatinine below 2.0 mg/dL

groups   0-4    5    6-7

Exact expression the calculator uses:

PLASMIC = (platelets_10e9_l<30) + hemolysis + (not active_cancer) + (not solid_organ_or_stem_cell_transplant) + (mcv_fl<90) + (inr<1.5) + (creatinine_mg_dl<2.0); each 1; max 7; bands 0-4 / 5 / 6-7

Inputs

Input	Scores 1 when	Unit
`platelets_10e9_l`	Below 30	×10^9/L
`hemolysis`	True	yes/no
`active_cancer`	False (no active cancer)	yes/no
`solid_organ_or_stem_cell_transplant`	False (no transplant history)	yes/no
`mcv_fl`	Below 90	fL
`inr`	Below 1.5	ratio
`creatinine_mg_dl` or `creatinine_umol_l`	Below 2.0 mg/dL	mg/dL or µmol/L

Hemolysis is a yes/no you set. Bendapudi defined it as a reticulocyte count above 2.5%, undetectable haptoglobin, or indirect bilirubin above 2.0 mg/dL.

How the calculation works

Lab items. Platelets, MCV, INR and creatinine each score 1 when strictly below the cut-off. A value exactly at the cut-off scores 0.
Hemolysis. Scores 1 when present.
Cancer and transplant. Each scores 1 when absent.
Add and group. Totals of 0 to 4 fall in the 0-4 group, 5 in the 5 group, and 6 or 7 in the 6-7 group.

The calculator returns the group label. It doesn't return a percentage for each group.

Units

Creatinine can go in as mg/dL or µmol/L. A µmol/L value is divided by 88.42 before it's compared with 2.0 mg/dL. Platelets are in ×10^9/L, the same number as thousands per microlitre.

Worked examples

These use Magent's own expected values for the calculator.

Example 1: all seven points

Platelets 15, hemolysis present, no active cancer, no transplant, MCV 85, INR 1.1, creatinine 1.0.
Every item scores 1.
Total 7, group 6-7.

Example 2: cancer and transplant both present

The same labs and hemolysis as Example 1, but active cancer and a transplant history are both true.
Those two items score 0. The other five score 1 each.
Total 5, group 5.

Example 3: values sitting exactly on the cut-offs

Platelets 15, hemolysis present, no cancer, no transplant, MCV 90, INR 1.5, creatinine 2.0.
MCV, INR and creatinine are exactly at their cut-offs, so none of them scores.
Total 4, group 0-4.

Example 4: platelets 29 versus 30

With every other item scoring 0, platelets of 29 score 1, for a total of 1.
Platelets of exactly 30 score nothing, for a total of 0. Both are in the 0-4 group.

History of the PLASMIC score

Bendapudi PK, Hurwitz S, Fry A and colleagues published the score in Lancet Haematology in 2017, in "Derivation and external validation of the PLASMIC score for rapid assessment of adults with thrombotic microangiopathies: a cohort study". They derived it in one cohort and tested it in another, using ADAMTS13 activity as the reference.

When it's used

The score is added up when an adult presents with signs of a TMA, such as low platelets with red cell breakdown, and ADAMTS13 activity isn't yet known.

Where it's used

Emergency departments, hospital wards and haematology services.

Who uses it

Haematologists and the physicians who first see the patient. The calculator applies the cut-offs, adds the points and assigns the group.

Limits of the calculation

It's a pretest grouping. It doesn't replace an ADAMTS13 result.
It's meant for adults with a suspected TMA, not for everyone with low platelets.
It doesn't return a percentage, and it doesn't choose what to do next.
Hemolysis, cancer and transplant are yes/no answers you supply; a wrong answer changes the total.
This page doesn't say what a result means for a particular person.

Clinical decisions belong to a qualified clinician who knows the patient.

4Ts estimates the pretest chance of heparin-induced thrombocytopenia, another cause of low platelets.
ISTH DIC and SIC score disseminated or sepsis-induced coagulopathy.
ANC works out the absolute neutrophil count.

Glossary

TMA: thrombotic microangiopathy, small-vessel clotting with red cell damage and low platelets.
TTP: thrombotic thrombocytopenic purpura, a TMA caused by severe ADAMTS13 deficiency.
ADAMTS13: an enzyme that trims von Willebrand factor.
MCV: mean corpuscular volume, the average size of red cells.
INR: international normalised ratio, a clotting time measure.

Common mistakes

Scoring cancer or transplant when present. The point goes to their absence.
Scoring values at the cut-off. Platelets 30, MCV 90, INR 1.5 and creatinine 2.0 all score 0.
Mixing creatinine units. Give mg/dL or µmol/L, and the calculator converts µmol/L.
Reading the group as a plan. The group describes pretest likelihood; it doesn't decide care.

Source

Bendapudi PK, 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. DOI: 10.1016/S2352-3026(17)30026-1. PMID: 28259520

Frequently asked questions

What does PLASMIC stand for?

Platelets, Lysis, Active cancer, Stem-cell or solid-organ transplant, MCV, INR and Creatinine.

What are the PLASMIC groups?

0-4, 5 and 6-7. Higher groups had more severe ADAMTS13 deficiency in Bendapudi's cohorts.

Why do cancer and transplant score when they are absent?

Both are linked with other causes of TMA. When neither is present, severe ADAMTS13 deficiency becomes more likely, so the point goes to their absence.

Does a platelet count of exactly 30 score?

No. Platelets score when strictly below 30.

Does the calculator give a percentage?

No. It returns the total and the group label.