Equis ISSN 2398-2977
Plasma: fibrinogen
Contributor(s): Robert Shull
Overview
- Fibrinogen: soluble plasma protein produced in hepatic parenchymal cells and stored until required.
- Free in blood normally accounting for approximately 5% of plasma protein.
- Acute phase reactant protein detectable from 48 hours after onset of inflammation and reaching peak levels within 5-7 days.
- Inflammation (bacterial, chemical, neoplastic, traumatic) increases [fibrinogen]. Increase temporary if acute, but may persist in chronic inflammation.
- Used in blood coagulation therefore decreases [fibrinogen] in disseminated intravascular coagulation (DIC) Disseminated intravascular coagulation and following major trauma/surgery.
Sampling
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Tests
Methodologies
Chemical method
- Thrombin + plasma → fibrin clot which is washed, dried and weighed. Time consuming and may be adversely affected by large amounts of heparin .
Turbidometric method
- Plasma + ammonium sulphate → precipitated fibrinogen → resulting turbidity measured photometrically.
Immunologic method
- Antifibrinogen is complexed with latex particles and mixed with diluted blood. Agglutination occurs at [fibrinogen] >10 g/l.
- Rapid, easy but not quantitative and does not differentiate fibrinogen from its breakdown products.
Thrombin time
- Measures plasma [functional fibrinogen]. Citrate anticoagulated plasma + thrombin → clotting; the time to reach standardized clotting is proportional to fibrinogen concentration.
Heat precipitation method
- EDTA + whole blood drawn into 2 microhematocrit tubes → tubes sealed at one end → centrifuge for 5 minutes in microhematocrit centrifuge → place one tube in water bath at 56°C for 3 minutes then centrifuge. Read total plasma protein (TPP) by refractometry for both tubes. The difference between the two results equals the fibrinogen concentration in grams/dl.
Availability
- All commercial laboratories.
- Some practice laboratories.
Validity
Sensitivity
Specificity
Predictive value
- Best used as part of a blood profile.
Technique (intrinsic) limitations
- Does not provide specific diagnoses.
Result Data
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Further Reading
Publications
Refereed papers
- Recent references fromPubMed.
- Labelle A L et al(2011)Effects of ophthalmic disease on concentrations of plasma fibrinogen and serum amyloid A in the horse. Equine Vet J43(4), 460-465PubMed.