Bloody Minded Episode 66 - In The Lab: D-Lightful | The D-Dimer
Oct 28, 2025
Explore the fascinating world of D-dimers, starting with their role as fibrin degradation products in clotting dynamics. Discover how various assays, like ELISA and POCT, measure D-dimer levels and what those results mean clinically. The hosts break down the differences between DDU and FEU units, and their implications in diagnosis. Learn about D-dimer’s connections to cancer and other conditions that can elevate levels, as well as its significance in pregnancy and aortic dissection diagnosis. It's a deep dive into the complexity of this crucial diagnostic tool!
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What The D-Dimer Actually Is
- D-dimer is a fibrin degradation product formed when plasmin breaks down cross-linked fibrin in clots.
- It reflects formation and degradation of cross-linked fibrin and thus indicates thrombotic activity but is not specific for VTE.
Role Of Factor XIII In Dimer Formation
- Factor XIIIa cross-links D-domains of fibrin monomers to create the D-dimer structure within clots.
- Without factor XIII activity (e.g., severe deficiency) D-dimers are not formed.
How Fibrinolysis Releases D-Dimer
- Plasmin, activated from plasminogen by tPA on the fibrin surface, digests cross-linked fibrin to release D-dimer into plasma.
- Circulating D-dimer has an approximate half-life of eight hours before renal and reticuloendothelial clearance.