Fibrinogen antigen

Description: 
Dysfibrinogenemias are qualitative disorders and can be detected by measuring both activity and protein concentration irrespective of function. Quantitative deficiencies of fibrinogen will generate concordant results but dysfibrinogenemias commonly generate an antigen result within the reference range.

Fibrinogen antigen is measured in a sandwich ELISA. Fibrinogen in test plasma captured by antibodies bound to microtitre plate wells, incubated, and unbound material then washed off. A solution of antibody to fibrinogen that is conjugated to an enzyme is added to ‘tag’ onto any captured fibrinogen. Unbound conjugate is washed off and a substrate for the enzyme is added, the product of the enzyme-substrate reaction being coloured. Colour intensity is in direct proportion to the degree of conjugate-binding, itself proportional to the amount of fibrinogen capture and thus, concentration.
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 that 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: 

1.97 - 4.76

Units: 
g/l
Sample type and Volume required: 
External requests: Citrated platelet poor plasma
400µL x 1 aliquot
Internal requests: please refer to EPR label
Turnaround time: 
14 - 21 days
Special sample instructions: 

The sample should be analysed or manipulated & stored in the laboratory 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.

Contacts:
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
24/7
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 09/03/2017