Q: How does the ISTH score guide treatment?

A score ≥5 in the right clinical context should prompt treatment of the underlying cause (e.g., antibiotics for sepsis, source control). Platelet and coagulation factor replacement is guided by bleeding, not by laboratory numbers alone. Anticoagulation for DIC is controversial and generally avoided.

Question 1

What conditions can mimic DIC and cause a false-positive ISTH score?

Accepted Answer

Chronic liver disease (thrombocytopenia, prolonged PT, low fibrinogen), massive transfusion (dilutional coagulopathy), and acute promyelocytic leukaemia (APML) can all meet ISTH DIC criteria without true DIC. Clinical correlation is essential.

Question 2

How should I score the fibrin-related marker if D-dimer is reported as a range?

Accepted Answer

Use the laboratory's upper normal limit. If the D-dimer is moderately elevated (2–5× ULN), assign 2 points. If strongly elevated (>5× ULN), assign 3 points. Many labs report D-dimer with an age-adjusted normal range.

Question 3

Does a low ISTH score rule out DIC?

Accepted Answer

Not definitively. In early or evolving DIC, the score may be <5. Serial scoring daily (or more frequently in unstable patients) is recommended. A rising score is more concerning than any single value.

Question 4

How does the ISTH score guide treatment?

Accepted Answer

A score ≥5 in the right clinical context should prompt treatment of the underlying cause (e.g., antibiotics for sepsis, source control). Platelet and coagulation factor replacement is guided by bleeding, not by laboratory numbers alone. Anticoagulation for DIC is controversial and generally avoided.