From the Guidelines
Elevation of Complement component 3 (C3) and Complement component 4 (C4) typically indicates an acute inflammatory response or an infectious process.
Key Points
- Elevated C3 and C4 levels are often seen in acute phase responses, which can be triggered by various factors, including infections, injuries, or inflammatory conditions 1.
- In the context of glomerulonephritis, an elevation of C3 and C4 may suggest an immune complex-mediated process, which can be associated with infections, autoimmune diseases, or other conditions 1.
- A thorough evaluation for underlying causes of antigenemia should be performed, including screening for infections, autoimmune diseases, and monoclonal gammopathies 1.
- It is essential to consider the clinical context and other laboratory findings, such as serum creatinine, urinalysis, and serologic tests, when interpreting elevated C3 and C4 levels 1.
Clinical Implications
- Elevated C3 and C4 levels should prompt a comprehensive clinical evaluation to identify underlying causes and guide further management.
- In patients with glomerulonephritis, treatment should focus on addressing the underlying cause, whether it be an infection, autoimmune disease, or other condition 1.
- A comprehensive complement analysis may be necessary to assist with the diagnosis of C3 glomerulopathy or other complement-mediated conditions 1.
From the Research
Elevation of Complement Component 3 (C3) and Complement Component 4 (C4)
Elevation of C3 and C4 can indicate various conditions, including:
- Chronic inflammation, such as rheumatoid arthritis and Crohn's disease, where elevated levels of C3 and C4 split products are observed 2
- Postnatal pregnancy-related venous thrombosis, where high levels of C3 and C4 are associated with an increased risk of venous thrombosis 3
- Diabetes mellitus, where elevated levels of C3 and C4 are found in diabetics and individuals with glucose intolerance 4
- Rheumatoid arthritis and spondyloarthritis, where elevated C3 levels are associated with disease activity and cardiometabolic risk factors 5
- Poor outcomes in living donor liver transplantation, where low levels of C3 at 2 weeks after transplantation are associated with increased 90-day mortality 6
Conditions Associated with Elevated C3 and C4
Some conditions associated with elevated C3 and C4 include:
- Rheumatoid arthritis
- Crohn's disease
- Diabetes mellitus
- Pregnancy-related venous thrombosis
- Spondyloarthritis
- Liver transplantation
Biomarker Potential
C3 and C4 may serve as biomarkers for: