D-dimer
D-dimer is a breakdown product of blood clots — it forms when the body breaks down a clot. Elevated means a clot formed (and broke down) somewhere, but it does not tell where.
| Rating | Range | What it means |
|---|---|---|
| Good | below 0.5 mg/L | Within range. |
| Worth improving | 0.5 – 1 mg/L | Slightly elevated — nonspecific. |
| Talk to a doctor | 1 mg/L and above | Elevated — rule out thrombosis; consult. |
Why it matters
ISTH: elevated with thrombosis (nonspecific); low helps rule out venous thrombosis.
If it’s low
Low D-dimer is useful — with a low clinical probability it strongly lowers the likelihood of a clot.
If it’s high
High D-dimer means recent formation/breakdown of a clot — but it is nonspecific: it is also raised by infection, injury, surgery, pregnancy, inflammation and age.
What to do
D-dimer is mainly a test to RULE OUT a clot and is not a screening test for healthy people. With symptoms (swollen, painful leg; sudden shortness of breath/chest pain) → URGENT care, do not wait for the result to be interpreted.
Read together with
Fibrinogen · Platelets
This content is for information only and is not a substitute for medical advice. Talk to your doctor about your results.
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