This test measures Complement C4, another immune protein essential for identifying immune complex–related diseases.
Diagnostic Value: Decreased C4 levels can indicate active lupus nephritis, membranoproliferative glomerulonephritis, or other complement-mediated kidney diseases.
Clinical Significance: Evaluating C4 alongside C3 provides a clearer picture of complement system activity and helps differentiate autoimmune from infectious causes of kidney inflammation.
Symptom Correlation: Patients may experience fatigue, swelling, foamy urine, or other signs of kidney involvement.
Because complement proteins are among the earliest markers of autoimmune renal inflammation, the C4 test supports early detection and effective disease monitoring.