This test measures the level of immune complexes bound to complement component C1q, a marker of immune system activation.
Diagnostic Value: Elevated C1q CIC levels indicate the presence of circulating immune complexes that may contribute to tissue inflammation and autoimmune disease activity, particularly in Systemic Lupus Erythematosus (SLE) and other immune complex–mediated conditions.
Clinical Significance: High values can reflect ongoing inflammation or active disease, and may correlate with flares in lupus or vasculitis.
Symptom Correlation: Patients may experience fatigue, joint pain, rashes, kidney involvement, or low complement levels on other tests.
Because immune complexes play a central role in many autoimmune reactions, the C1q CIC test helps evaluate disease activity and tissue damage in immune-mediated disorders.