Complement Component 3 (C3)
Complement C3 is the central convergence point for the classical, alternative, and lectin complement activation pathways of the innate immune system.
Standard vs. Optimal Reference Rangesmg/dL
Standard reference intervals represent the statistical 95% distribution of unselected commercial populations. Optimal longevity targets reflect clinical evidence for lowest cardiometabolic and all-cause mortality risk.
Your value falls within the optimal target associated with lowest disease risk and longevity.
90 - 180 mg/dL
General reference distribution across unselected commercial populations.
100 - 160 mg/dL
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
C3 convertase cleaves C3 into C3a (anaphylatoxin) and C3b (opsonin). C3b facilitates phagocytosis and assembles C5 convertase to form the membrane attack complex (C5b-9).
Differential Diagnosis
Elevated Levels (C3 High)
- •Acute-phase inflammatory response (C3 is a positive acute-phase reactant)
- •Obesity and metabolic syndrome (adipocyte C3 synthesis)
Low Levels (C3 Low)
- •Active Systemic Lupus Erythematosus flare (immune complex consumption)
- •Post-streptococcal glomerulonephritis
- •Membranoproliferative glomerulonephritis
Technical Reference & Deep Dive
Biochemistry & Enzymatic Pathways
Longevity Risk Architecture & Epidemiology
Pre-Analytical Caveats & Diagnostic Workup
Pre-Analytical Considerations:
Venipuncture should be performed when the patient is in a baseline non-acute health state, free from acute respiratory or viral infections for at least 4 weeks. A 12-hour fast is required if blood is also being analyzed for comprehensive metabolic and lipid panels. Ensure sample is processed at room temperature for Erythrocyte Sedimentation Rate within 4 hours of collection.
Reflexive Testing Protocol:
- High-sensitivity C-Reactive Protein (hs-CRP) and Erythrocyte Sedimentation Rate (ESR) for systemic inflammatory quantification
- Full 9-biomarker Yale PhenoAge composite calculation (Albumin, Creatinine, Glucose, hs-CRP, Lymphocyte %, MCV, RDW, ALP, WBC)
- Comprehensive Autoimmune Serology (ANA with reflex IFA titer, Anti-dsDNA, ENA panel, Complement C3 and C4)
- DNA Methylation Epigenetic Clock (DunedinPACE, GrimAge v2) to measure biological pace of aging and organ-specific age acceleration
- Circulating Senescence Biomarker Panel (p16INK4a, circulating SASP cytokines IL-6, TNF-alpha, MCP-1)
Clinical Citations & Primary Literature (1)
- [1]The Complement System in Innate Immunity, Autoimmunity, and Aging - Nature Immunology (2021). PMID: 33878270
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Complement Component 3 (C3) into overall healthspan optimization.