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C1q Antibody, IgG

2007601

Anti-C1q Antibody, IgG 2007601

Method

Semi-Quantitative Enzyme-Linked Immunosorbent Assay

Assess risk for lupus nephritis development in individuals with SLE
Assess global SLE disease activity

Systemic lupus erythematosus (SLE) is an autoimmune disease with multiorgan involvement. Approximately 37-45% of patients with SLE will develop lupus nephritis, which negatively impacts patient survival. Testing for C1q antibodies assists in evaluating the risk of lupus nephritis development.

Disease Overview

Physiology

C1q antibodies are associated with active glomerulonephritis in patients with SLE. The presence of antibodies in patients with SLE indicates a higher risk for developing severe clinical manifestations of the disease. Specifically, the presence of C1q antibodies correlates with renal activity and flares, and the absence of antibodies indicates a low probability of lupus nephritis.

Test Interpretation

Sensitivity/Specificity

Clinical sensitivity and specificity vary based on disease population and disease state
Analytical sensitivity and specificity vary based on disease population and disease state as well as testing platform

Results

Negative: 0-19 units
Equivocal: 20-39 units
Positive: ≥40 units

Limitations

Not all patients with lupus nephritis will be positive for C1q antibodies
The presence of C1q antibodies is not specific for SLE

References

31406264

Albuquerque BC, Salles VB, Tajra RDP, et al. Outcome and Prognosis of Patients With Lupus Nephritis Submitted to Renal Transplantation. Sci Rep. 2019;9(1):11611.

24497353

Wener MH. Tests for circulating immune complexes. Methods Mol Biol. 2014;1134:47-57.

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