Fibrinogen activity (Clauss)

The Clauss fibrinogen assay is a measure of function. It is performed on a dilution of test plasma to reduce or eliminate interference by substances such as heparin and fibrin degradation products. Diluted plasma is clotted with a high concentration thrombin, the clotting time being directly proportional to the fibrinogen activity.
Clinical details: 
The final stage in the molecular co-operation of the procoagulant participants of secondary haemostasis is the conversion of soluble fibrinogen monomers to insoluble, cross-linked fibrin polymers to stabilse the blood clot. Fibrinogen is a large, symmetrical dimeric glycoprotein composed of two identical sub-units, each of which is comprised of three non-identical polypeptide chains. It is present in plasma at a high concentration and is also contained in platelet α-granules. Fibrin is formed by thrombin cleavage of the small fibrinopeptides A & B from intact fibrinogen molecules that exposes donor sites which interlock with complementary unshielded acceptor sites on adjacent molecules to promote polymerisation.

Quantitative and qualitative deficiencies of fibrinogen can be congenital or acquired and give rise to bleeding. More rarely, some dysfibrinogenemias can predispose to thrombosis.
Reference range: 

"Automated Clauss 1.7 - 3.9 Manual Clauss 1.5 - 3.2"

Sample type and Volume required: 
External requests: Citrated platelet poor plasma
420µL x 1 aliquot
Internal requests: please refer to EPR label
Turnaround time: 
4 hours
Special sample instructions: 

The sample should be analysed within 4 hours of venepuncture. Please ensure sample tubes are filled exactly to the fill-line as underfilling creates a dilution error and leads to inaccurate results.

Diagnostic Haemostasis and Thrombosis Department
020 7188 2797
St Thomas' Hospital
North Wing - 4th and 5th Floors
Westminster Bridge Road
London SE1 7EH

Laboratory opening times
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 09/03/2017