From the Guidelines
Raised plasma viscosity and fibrinogen levels are indicative of an acute phase response, suggesting inflammation, infection, or tissue damage in the body. Plasma viscosity measures the thickness of blood plasma, while fibrinogen is a protein produced by the liver that helps with blood clotting 1. When these values are elevated, it typically suggests an inflammatory response, which can be caused by various factors such as infections (bacterial, viral), inflammatory disorders (rheumatoid arthritis, inflammatory bowel disease), tissue injury, malignancies, and cardiovascular diseases.
The elevation of plasma viscosity and fibrinogen occurs because during inflammation, the liver increases production of acute phase proteins, including fibrinogen, which makes the blood more viscous 1. This can lead to an increased risk of thrombosis and other cardiovascular complications. It is essential to investigate the underlying cause of the elevated levels through additional tests, rather than treating these markers directly.
Some possible causes of elevated plasma viscosity and fibrinogen levels include:
- Infections (bacterial, viral)
- Inflammatory disorders (rheumatoid arthritis, inflammatory bowel disease)
- Tissue injury
- Malignancies
- Cardiovascular diseases Treatment will focus on addressing the underlying condition causing the inflammation, rather than the elevated plasma viscosity and fibrinogen levels themselves. Monitoring disease activity and treatment response using these markers can be useful, but it is crucial to use them in conjunction with other inflammatory indicators, such as C-reactive protein 1.
In clinical practice, viscoelastic tests, such as thromboelastometry, can provide a fair estimation of fibrinogen activity and contribution to the clot, even during conditions like cardiac surgery with bypass 1. These tests can help guide fibrinogen replacement therapy and improve patient outcomes. However, the definition of transfusion triggers for fibrinogen supplementation and the evaluation of the effectiveness of the intervention require reliable and reproducible assays 1.
From the Research
Raised Plasma Viscosity and Fibrinogen Level
A raised plasma viscosity and fibrinogen level can be indicative of several health issues, including:
- Increased risk of vascular events, such as myocardial infarction and ischemic stroke 2
- Poor outcome in patients with acute ischemic stroke after intravenous thrombolysis 3
- Increased risk of subsequent ischemic events and major bleeding in stable outpatients with peripheral arterial disease 4
Association with Cardiovascular Disease
The association between elevated plasma fibrinogen and increased risk for myocardial infarction is well established, but the nature of this association is subject to debate 5. Some studies suggest that elevated plasma fibrinogen may be a cause or consequence of cardiovascular disease, while others indicate that it may be a marker of vascular risk 2.
Potential Mechanisms
The potential mechanisms by which raised plasma fibrinogen levels contribute to increased risk of vascular events include:
- Adverse effects on plasma viscosity, coagulation, platelet activity, inflammation, and atherogenesis 2
- Increased platelet activation and aggregation 3
- Enhanced thrombus formation and stability 6
Clinical Implications
The clinical implications of raised plasma viscosity and fibrinogen level include: