C4 complement

This is an important test to help diagnose autoimmune conditions such as SLE and rheumatoid arthritis.

Finger-prick blood
1 tests included
4 days turnaround



About C4 complement

What is complement C4?

Complement C4 is a protein central to the complement system, a term for a group of proteins in the blood and body fluids which are part of the innate immune system. The complement system helps the body to fight infections by promoting inflammation, facilitating removal of pathogens, such as bacteria and clearance of cell debris. 

Abnormal C4 levels are associated with autoimmune conditions, such as systemic lupus erythematosus (SLE), and rheumatoid arthritis.

Why take this test?

This test measures the levels of C4 in the blood and may be used to help diagnose autoimmune conditions such as SLE and rheumatoid arthritis.

What's tested


How it works



Purchase your Kit

Just order a test online and get your kit delivered right to your door unless you are ordering a COVID-19 Fit to Fly test where you will be given appointment options to attend our clinics across the United Kingdom for a nose and throat swab PCR test at the checkout stage.



Take your test and post

Follow our simple instructions to take your sample and post back the enclosed prepaid envelope to our accredited lab for processing. We also offer home or workplace visits by a qualified nurse. For COVID-19 Fit to Fly tests you must attend one of our partner clinics for our trained collection officers to take your sample. You will then have the results emailed to you.



Get results directly to your dashboard

You will receive an email notification from our medical team when your results are available on your secure personalised health dashboard.