Complement Component 4 (C4)

Three reasons the Complement C4 test is right for you

• This test measures the level of complement component C4, an essential protein involved in your immune system’s defense mechanisms
• It helps detect immune system abnormalities that may indicate autoimmune disorders, chronic inflammation, or infections
• Results assist your healthcare provider in monitoring disease progression and evaluating treatment effectiveness

What is the Complement C4 test?

The Complement C4 test measures the concentration of C4 protein in your blood. C4 is a key component of the classical pathway of the complement system, which helps your body fight infections and clear immune complexes. Abnormal C4 levels can suggest immune system dysregulation or consumption due to disease activity.

This test is often recommended for:

• Individuals with suspected autoimmune diseases such as lupus or rheumatoid arthritis
• Patients experiencing unexplained inflammation or recurrent infections
• Monitoring complement activity in kidney disorders or liver conditions
• Evaluating immune system function during treatment for autoimmune or inflammatory diseases

What are the symptoms of abnormal C4 levels?

Abnormal C4 levels may not directly cause symptoms, but they can be associated with underlying conditions. Possible signs include:

• Frequent infections or slow recovery from illness
• Swelling, joint pain, or unexplained rashes
• Fluctuating fatigue or weakness
• Kidney abnormalities, such as protein in the urine or swelling
• Exacerbation of autoimmune disease symptoms

How does the Complement C4 test work?

A blood sample is taken and analysed to measure the amount of C4 protein. Low levels may indicate increased consumption due to autoimmune activity, while elevated levels can be a response to inflammation or infection. The results give insight into the activity of the classical complement pathway and assist in disease monitoring and diagnosis.

What can I expect at my appointment?

Your appointment involves a standard blood draw performed by a trained healthcare professional. The procedure is quick, safe, and minimally invasive.

Results are typically available within 1–2 days. You will receive a report showing your C4 levels and guidance from your healthcare provider regarding any necessary follow-up or further testing.

Are there any risks with this test?

This is a routine blood test and is very safe. Most people experience only mild discomfort at the needle site.

Minor bruising or tenderness may occasionally occur. Serious complications are extremely rare. Seek medical advice if you feel unwell after the test.

How do I schedule my appointment?

To book your appointment, click the “Book Your Appointment” button at the top of the page. Select your preferred clinic, date, and time, and we will guide you through the process.