Complement C3, Serum

Laboratory assay overview

The antinuclear antibodies test detects autoantibodies that bind to the nuclear components of HEp-2 cells. A positive antinuclear antibodies titer is not specific but indicates the presence of one or more autoantibodies. Profiles of specific autoantibodies have diagnostic and potential prognostic utility for several autoimmune diseases. This profile helps differentiate between eight autoimmune disease states: SLE • Antinuclear antibodies by IFA Tests with high specificity • Anti‐dsDNA by Farr • Anti‐SM Tests with moderate specificity • Anti‐Ro • Anti‐La • Anti‐Chromatin • C3 & C4 Complements • Anticardiolipin IgG, IgA & IgM Drug‐induced SLE • Anti‐Chromatin Sjogren’s Syndrome • Anti‐Ro • Anti‐La Rheumatoid Arthritis • Anti‐CCP (high specificity) • Rheumatoid Factor (Turbidimetry) Mixed Connective Tissue Disease (MCTD) • Anti-U1 RNP Limited Scleroderma (CREST) • Anti-Centomere Diffuse Scleroderma • Anti-SCL-70 by EIA, confirmed by a second method Autoimmune Thyroid Disease • Anti-Thyroid Microsomal (TPO)

Laboratory assay overview

The antinuclear antibodies test detects autoantibodies that bind to the nuclear components of HEp-2 cells. A positive antinuclear antibodies titer is not specific but indicates the presence of one or more autoantibodies. Profiles of specific autoantibodies have diagnostic and potential prognostic utility for several autoimmune diseases. This profile helps differentiate between eight autoimmune disease states: SLE • Antinuclear antibodies by IFA Tests with high specificity • Anti-dsDNA by Farr • Anti-SM Tests with moderate specificity • Anti-Ro • Anti-La • C3 & C4 Complements • Anticardiolipin IgG, IgA & IgM Sjogren’s Syndrome • Anti-Ro • Anti-La Mixed Connective Tissue Disease (MCTD) • Anti-U1 RNP Limited Scleroderma (CREST) • Anti-Centromere Diffuse Scleroderma • Anti-SCL-70 by EIA, confirmed by a second method Autoimmune Thyroid Disease

Laboratory assay overview

Measurement of C3 is used to detect individuals with inborn deficiency of this factor or those with immunologic disease in whom complement is consumed at an increased rate. These include lupus erythematosus, chronic active hepatitis, certain chronic infections, post-streptococcal and membranoproliferative glomerulonephritis, and others.

Laboratory assay overview

Quantitation of C3 is used to detect individuals with inborn deficiency of this factor or those with immunologic disease in whom complement is consumed at an increased rate. These include lupus erythematosus, chronic active hepatitis, certain chronic infections, poststreptococcal and membranoproliferative glomerulonephritis, and others.

Labcorp population reference ranges

Labcorp calculates these statistical intervals for this specific assay and demographic group, not as universal optimal targets.

Laboratory assay overview

This panel may be useful in evaluating patients with clinical suspicion of systemic lupus erythematosus (SLE). This panel includes measurements of complement component 3 (C3), complement component 4 (C4), and total hemolytic complement (CH50). Low levels of C3 and/or C4 are included in the 2019 SLE classification criteria from EULAR (European League Against Rheumatism/American College of Rheumatology) [1], whereas the 2012 Systemic Lupus International Collaborating Clinics classification criteria for SLE include low levels of C3, C4, or CH50 [2]. Without SLE diagnostic criteria in place, SLE classification criteria are often used by clinicians to guide diagnosis. However, the current classification criteria have not been tested for diagnostic purposes and should not be used alone to exclude the diagnosis of SLE [1,2]. Other immunologic biomarkers that may aid in the diagnosis of SLE include antinuclear antibodies and specific antibodies to double-stranded DNA and Smith [3]. Measurement of C3 and C4 may also help monitor activity and remission of SLE [4]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. ⁠⁠⁠⁠⁠⁠⁠References 1. Aringer M, et al. Arthritis Rheumatol. 2019;71(9):1400-1412. 2. Petri M, et al. Arthritis Rheum. 2012;64(8):2677-2686. 3. Kavanaugh A, et al. Arch Pathol Lab Med. 2000;124(1):71-81. 4. Mosca M, et al. Ann Rheum Dis. 2010;69(7):1269-1274.

Laboratory assay overview

Decreased C3 may be associated with acute glomerulonephritis, membranoproliferative glomerulonephritis, immune complex disease, active systemic lupus erythematosis, and generalized autoimmune processes.

Quest Diagnostics population reference ranges

Quest Diagnostics calculates these statistical intervals for this specific assay and demographic group, not as universal optimal targets.

Laboratory assay overview

Decreased concentrations of both C3 and C4 suggest activation of the classical pathway, whereas decreased concentration of just C3 suggests activation of the alternative pathway. Both complement factors may be used to monitor activity of patients with systemic lupus erythematosus (SLE) and immune complex-induced vasculitis.

Laboratory assay overview

ANA are commonly present in a variety of autoimmune diseases. ANA frequency also increases with age in apparently healthy people. ANA patterns on HEp-2 slides provide general clues about particles (chromatin, nucleosomes, and spliceosomes). The Farr assay is the most specific method for detecting dsDNA autoantibodies. Significant elevations in dsDNA autoantibody concentrations confirm the diagnosis of systemic lupus erythematosus (SLE). Serial studies of elevated values of dsDNA auto antibodies are useful for predicting activity of SLE. Anti-MPO autoantibodies aid in assessment of certain autoimmune vasculitides such as microscopic polyarteritis, and crescentic glomerulonephritis. Elevated levels of Anti-PR-3 antibodies are classically observed in patients with Wegener granulomatosis (WG), particularly with active disease, and less frequently in other forms of necrotizing vasculitis. Anti-GBM autoantibodies are recognized as being important in the pathogenesis of the rapidly progressive glomerulonephritis of Goodpasture's syndrome. Measurements of C3 and C4 are used to detect individuals with inborn deficiency of this factor or those with immunologic disease in whom complement is consumed at an increased rate. These include lupus erythematosus, chronic active hepatitis, certain chronic infections, post-streptococcal and membranoproliferative glomerulonephritis, and others.

Laboratory assay overview

This profile is comprised of ANA by IFA, Anti-dsDNA by Farr(RIA), Anti-Sm, Anti-U1 RNP, Anti-Ro (SS-A), Anti-La (SS-B), Anti- Chromatin, and C3 and C4. It may be useful in diagnosing systemic lupus erythematosus (SLE).

Laboratory assay overview

This profile is used to aid in monitoring treatment for Lupus patients.

Laboratory assay overview

ANA are commonly found in a variety of autoimmune diseases. Antibody frequency increases with age in apparently healthy people. ANA patterns on HEp-2 slides provide only general clues about particles (chromatin, nucleosomes, and spliceosomes). The Farr assay is the most specific method of detecting dsDNA autoantibodies. Significant elevations in dsDNA autoantibody concentrations confirm the diagnosis of systemic lupus erythematosus (SLE). Serial studies of elevated values of dsDNA auto antibodies are useful for predicting activity of SLE. Anti-MPO autoantibodies aid in assessment of certain autoimmune vasculitides such as microscopic polyarteritis, and crescentic glomerulonephritis. PR-3 is the major target antigen of antineutrophil cytoplasmic autoantibodies (ANCA) that give a cytoplasmic (C-ANCA) autoantibodies (ANCA) which give a perinuclear (pANCA) immunofluorescence pattern. Anti-PR-3 autoantibodies aid in the assessment of certain autoimmune vasculitides such as microscopic polyartheritis and crescentic glomerulonephritis. PR-3 is the major target antigen of antineutrophil cytoplasmic autoantibodies (ANCA) that give a cytoplasmic (C-ANCA) immunofluorescence pattern. Elevated levels of Anti-PR-3 are classically observed in patients with Wegener granulomatosis (WG), particularly with active disease, and less frequently in other forms of necrotizing vasculitis. ANTI-GBM autoantibodies are recognized as being important in the pathogenesis of the rapidly progressive glomerulonephritis of Goodpasture's syndrome. Measurements of C3 and C4 are used to detect individuals with inborn deficiency of this factor or those with immunologic disease in whom complement is consumed at an increased rate. These include lupus erythematosus, chronic active hepatitis, certain chronic infections, poststreptococcal and membranoproliferative glomerulonephritis, and others.