Long COVID Atlas
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Plain-language first, with specialist detail below. For understanding, not medical advice.

Long COVID Atlas › Glossary › Fibrinaloid microclots

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Fibrinaloid microclots

https://longcovidatlas.org/glossary/microclots

In plain language

What it is

Tiny abnormal blood clots, too small to see on a normal scan, made of a misfolded form of the clotting protein fibrin.

Why it matters

They resist the body's normal clot-clearing and may block the smallest vessels, though their exact role is disputed.

Think of it like

Sticky grit in the smallest pipes that the usual cleaning crew cannot dissolve.

A self-reinforcing microclot loop Endothelial lining injured Tissue factor exposed,platelets activated Fibrinaloid microclots form(resist normal breakdown) Capillaries blocked,lining injured further each step feeds the next
Microclots are not a separate event from endothelial injury, they are a loop. A damaged lining exposes tissue factor and activates platelets, which form fibrinaloid microclots that resist normal breakdown, and those clots block capillaries and injure the lining further, feeding the next turn. Whether these clots are reliably detectable and clinically decisive is still contested.

For specialists

Formal definition

Amyloid (misfolded) fibrin aggregates that trap other proteins and resist fibrinolysis; proposed to impair capillary perfusion in long COVID.

Mechanism

Spike protein and inflammation can drive fibrin into an amyloid form; whether these are a cause, a consequence, or reliably measurable is contested.

Sources

Related terms

FibrinolysisEndothelial dysfunctionSpike protein