Answer · biomarkers

What is D-dimer?

Name: What is D-dimer?
Creator: Laura Purdy

Short answer

D-dimer is a fibrin breakdown fragment used primarily to exclude venous thromboembolism. Elevated D-dimer is sensitive but not specific.

Reviewed by Dr. Laura PurdyMay 29, 2026

Full answer

D-dimer is produced when cross-linked fibrin in a clot is broken down by plasmin. Its dominant clinical role is exclusion of deep vein thrombosis and pulmonary embolism in acute settings — a low D-dimer in a low-pretest-probability patient effectively rules out venous thromboembolism. Many other conditions raise D-dimer, including infection, malignancy, pregnancy, recent surgery, and chronic inflammation. Age-adjusted cutoffs improve specificity in older adults. D-dimer is not a wellness marker and is not part of routine optimization panels.

Educational. Not a substitute for individualized provider review.

References & sources

D-dimer — Primary source · oMeds
Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29

Primary source

D-dimer