Description
Why It’s Done
The C4 test is ordered to:
1. Diagnose and Monitor Autoimmune Diseases
• Conditions like systemic lupus erythematosus (SLE), rheumatoid arthritis, and vasculitis can cause abnormal complement levels.
• Low C4 levels may indicate ongoing inflammation or immune system activation.
2. Evaluate Complement Deficiencies
• To detect inherited or acquired deficiencies in complement proteins that increase susceptibility to infections.
3. Assess Disease Activity
• In autoimmune disorders, C4 levels can help monitor disease activity and response to treatment.
4. Investigate Angioedema
• To help diagnose hereditary angioedema, a rare condition linked to C4 deficiency.
Preparation
1. Fasting
• Usually, no fasting is required for the C4 test.
2. Medications
• Inform your healthcare provider about any medications you are taking, especially immunosuppressants or steroids, as they may affect results.
3. Sample Collection
• A blood sample will be drawn from a vein in your arm.
• The procedure is quick and minimally invasive
