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C1q Antibody (IgG)
Test Code34303
CPT Codes
83516
Preferred Specimen
0.5 mL serum collected in a red-top tube (no gel)
Minimum Volume
0.3 mL
Other Acceptable Specimens
Plasma collected in: Sodium heparin (green-top) tube or EDTA (lavender-top) tube
Transport Container
Transport tube
Transport Temperature
Room temperature
Specimen Stability
Room temperature: 7 days
Refrigerated: 14 days
Frozen: 42 days
Refrigerated: 14 days
Frozen: 42 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Serum separator tube (SST)
Methodology
Enzyme Linked Immunosorbent Assay (ELISA)
FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
Setup Schedule
Sun, Thurs
Report Available
2-5 days
Reference Range
<26 RU/mL
Clinical Significance
This assay serves as a non-invasive aid for the diagnosis of active proliferative lupus nephritis (LN) and for monitoring disease activity. Autoantibodies to C1q (C1q Ab; IgG isotype) are detected in a number of autoimmune and infectious diseases but are best described in patients with systemic lupus erythematosus (SLE). Several studies suggest that C1q Ab plays a pathogenic role in the development of LN and that serum levels correlate with disease activity [1]. Moreover, C1q Ab results demonstrate fair sensitivity and specificity for active proliferative LN [2]. In addition, C1q Ab levels may begin to rise in advance of a renal flare and absence of C1q Ab suggests that a flare is unlikely [3].
References
1. Bock M, Heijnen I, Trendelenburg M. Anti-C1q antibodies as a follow-up marker in SLE patients. PLoS One. 2015;10(4):e0123572. doi:10.1371/journal.pone.0123572
2. Yin Y, Wu X, Shan G, et al. Diagnostic value of serum anti-C1q antibodies in patients with lupus nephritis: a meta-analysis. Lupus. 2012;21(10):1088-1097. doi:10.1177/0961203312451202
3. Fatemi A, Samadi G, Sayedbonakdar Z, et al. Anti-C1q antibody in patients with lupus nephritic flare: 18-month follow-up and a nested case-control study. Mod Rheumatol. 2016;26(2):233-239. doi:10.3109/14397595.2015.1074649
References
1. Bock M, Heijnen I, Trendelenburg M. Anti-C1q antibodies as a follow-up marker in SLE patients. PLoS One. 2015;10(4):e0123572. doi:10.1371/journal.pone.0123572
2. Yin Y, Wu X, Shan G, et al. Diagnostic value of serum anti-C1q antibodies in patients with lupus nephritis: a meta-analysis. Lupus. 2012;21(10):1088-1097. doi:10.1177/0961203312451202
3. Fatemi A, Samadi G, Sayedbonakdar Z, et al. Anti-C1q antibody in patients with lupus nephritic flare: 18-month follow-up and a nested case-control study. Mod Rheumatol. 2016;26(2):233-239. doi:10.3109/14397595.2015.1074649
Performing Laboratory
| Quest Diagnostics Nichols Institute-San Juan Capistrano, CA |
| 33608 Ortega Highway |
| San Juan Capistrano, CA 92675-2042 |
Last Updated: November 6, 2024
