Complement C3



Quest Diagnostics Test Code: 351

Decreased C3 is associated with acute glomerulonephritis, membranoproliferative glomerulonephritis, immune complex disease, active systemic lupus erythematosus, and generalized autoimmune processes.

The complement system is a system made up of a handful of proteins that help to promote immune and inflammatory responses. It makes up part of the innate immune system. Complement proteins’ main role is to destroy pathogens like bacteria and viruses. Testing for complement measures their level in the blood which can point to diseases like autoimmune diseases. Complement component 3 (C3) is the most common and abundant complement protein. C3 is responsible for attaching to microbes to destroy them. However, abnormal levels of C3 can also be found in autoimmune diseases like systemic lupus erythematosus.

This test is performed in following conditions such as:

• Butterfly rash on the face
• Mouth ulcers
• Loss of hair
• Extreme tiredness
• Joint pain and swelling
• Pain in your chest when breathing deeply


Specimen Collected
  • Blood
Estimated Time Taken

Turnaround for this test is typically 1-3 business days.