Examinations
Examinations
Complement C3 is a key protein of the complement system, which is part of the immune response. It plays a central role in inflammation and immune defense, being involved in both the classical and alternative pathways of complement activation.
Clinical Significance
- C3 is an acute-phase protein, meaning its levels increase during inflammation, infection, and tissue damage.
- It constitutes about 70% of the complement system, making it a critical factor in immune regulation and autoimmune disease development.
- C3 deficiency can lead to immune dysfunction, increasing susceptibility to bacterial infections and autoimmune diseases such as systemic lupus erythematosus (SLE) and vasculitis.
- Take the test at least 2 hours after the last meal.
- Avoid smoking for 1 hour before the test.
- Avoid physical and emotional stress for 1 hour before the test.
- Suspected hereditary complement deficiency
- Monitoring autoimmune diseases (e.g., lupus, vasculitis, rheumatoid arthritis)
- Suspected inflammatory or secondary bacterial infections, including:
- Systemic lupus erythematosus (SLE)
- Vasculitis
- Bacterial endocarditis
- Post-streptococcal glomerulonephritis
- Gram-negative sepsis
Elevated C3 Levels May Indicate:
- Active inflammation and infections
- Autoimmune connective tissue diseases (e.g., rheumatoid arthritis, rheumatic fever)
- Diabetes
- Myocardial infarction (heart attack)
- Gastrointestinal diseases (e.g., viral hepatitis, inflammatory bowel disease, ulcerative colitis)
- Thyroid disorders (e.g., goiter, thyroiditis)
Decreased C3 Levels May Indicate:
- Hereditary complement deficiency
- Autoimmune diseases (e.g., active phase of lupus)
- Severe bacterial infections (e.g., endocarditis, sepsis, parasitemia)
- Acute liver inflammation (e.g., hepatitis B)
- Post-streptococcal glomerulonephritis
- Familial Mediterranean fever
- HIV/AIDS