# Complement C4

> This test measures the level of Complement C4, a protein that works with your immune system to fight infections and manage inflammation. It helps show if your body is using up this protein too quickly, which often happens during active inflammation or autoimmune reactions. Results can help doctors evaluate conditions like lupus or kidney disease. However, this test does not diagnose a specific disorder on its own and is usually interpreted alongside other immune system tests.

- Labcorp code: 001834
- Category: [Autoimmunity](https://app.picardo.health/labs/tests/autoimmunity.md)
- Price: shown at checkout, before payment.
- Blood draw: free at a Labcorp location, or $75.00 at home.
- Order link: https://app.picardo.health/labs/order?tests=001834&ref=assistant

## About ordering

A licensed physician reviews every order before any test is run, and results arrive in the person's Picardo account. Ordering is open to adults 18 and over in the US, except New York, New Jersey, Rhode Island, Pennsylvania, Maryland, Massachusetts, Hawaii and Maine. General health information, not medical advice.