C3 COMPLEMENT

What this test checks

C3 is part of the complement system — proteins that help your immune system kill bacteria. Low or high C3 can indicate immune diseases like lupus, kidney disease, or chronic infections.

Why do people get this test?

Used in diagnosing and monitoring autoimmune diseases like lupus and certain kidney diseases.

When you should consider this test

• Diagnosed with or suspected lupus (SLE)
• Unexplained kidney inflammation
• Recurring infections

How to prepare

No fasting needed.