Special Edition Spring 2026 Sysmex News - Lab Week Edition - Flipbook - Page 15
Spring 2026
Science of Sysmex - Hemostasis
Fibrinogen: A Key Player in Blood Clot Formation
Fibrinogen is one of the most
important proteins in human blood,
serving as the essential raw material
the body transforms into 昀椀brin, the
structural “mesh” that stabilizes
blood clots. Although it receives far
less public attention than cholesterol
or glucose, 昀椀brinogen is central to
how the body stops bleeding and
responds to injury.
Synthesis and Circulation
Fibrinogen is produced in the liver
and circulates in plasma in a soluble
form. Under normal conditions, it
remains inactive, ready to be rapidly
Fig. 1: Figure 1: Thrombin-induced 昀椀brin formation.
converted when needed.
Because its production increases in response to in昀氀ammation or physiological stress, 昀椀brinogen is
considered an acute phase reactant, meaning levels can rise during infection, pregnancy, obesity or
chronic disease.
Role in the Coagulation Cascade
When blood vessels are injured, the enzyme thrombin plays the key role of converting 昀椀brinogen
into 昀椀brin. Thrombin removes 昀椀brinopeptides A and B, triggering the exposed binding sites to link
together and form a 昀椀brin mesh; this, in turn, provides structural support to the initial platelet clot by
forming a scaffold-like structure around the platelets.
However, this initial polymerization of 昀椀brin is unstable and requires factor XIII to cross-link the 昀椀brin
to form a stable structure (Figure 1). Subsequently, the trapped platelets migrate out of the 昀椀brin
mesh and are replaced by red blood cells, which are tightly packed after clot retraction. The end
result is a very stable and solid red clot that seals the injury for wound repair.
Read more about the importance of 昀椀brinogen testing here or
listen to Sysmex’s “Lab Talk” podcast series on YouTube.
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