C4 Blood Test

What is a C4 Blood Test?

The C4 Blood Test is a diagnostic test that measures the level of Complement C4 protein in your blood serum.
C4 is produced by the liver and plays a critical role in the immune system’s ability to fight infection, clear damaged cells, and regulate inflammation.

Doctors use this test to assess how well your immune system is working and to help diagnose autoimmune diseases such as Systemic Lupus Erythematosus (SLE), rheumatoid arthritis, or glomerulonephritis.

Low or high levels of C4 can indicate immune system dysfunction, ongoing inflammation, or recovery from infection.

What Does the C4 Test Measure?

This test measures the C4 protein concentration in the blood, which is part of the complement pathway of the immune system.

It helps your doctor to:

• Evaluate immune system activity
• Diagnose autoimmune disorders such as lupus or vasculitis
• Monitor the progression or treatment response of autoimmune diseases
• Assess inflammation and infection-related immune responses
• Detect hereditary complement deficiencies or angioedema

Who Should Get a C4 Blood Test and Why It’s Done

When is a C4 Blood Test Recommended?

Your doctor may recommend this test if you experience:

• Fatigue, muscle pain, or joint swelling
• Unexplained skin rashes or facial redness
• Persistent or recurrent infections
• Kidney problems or swelling
• Signs of autoimmune disease such as lupus
• Inflammatory symptoms that do not resolve

Who Needs This Test?

The C4 Blood Test is useful for:

• Individuals with suspected autoimmune disorders
• Patients being monitored for lupus or rheumatoid arthritis
• People with unexplained inflammation or chronic infections
• Individuals with hereditary angioedema or immune deficiency
• Patients with kidney inflammation (glomerulonephritis)

Why is a C4 Blood Test Done?

The test helps to:

• Diagnose autoimmune diseases such as lupus or rheumatoid arthritis
• Monitor disease activity during treatment
• Evaluate the cause of inflammation or immune deficiency
• Identify hereditary complement system disorders
• Support diagnosis in patients with angioedema or glomerular disease

C4 levels are often tested along with C3 Complement Test for a more comprehensive immune assessment.

Importance of the C4 Blood Test

The C4 Blood Test is important because it provides insight into your immune system’s ability to respond to infection or inflammation.
Low C4 levels may suggest active disease or immune system overactivity, while high levels may indicate recovery or ongoing inflammation.

Regular monitoring helps doctors adjust treatment for autoimmune conditions and track response to therapy.

C4 Blood Test Booking and Reports – Metropolis Healthcare

How to Book the C4 Blood Test

1. Online Booking
   Book your C4 Blood Test via the Metropolis Healthcare website or mobile app. Choose your preferred location or book home sample collection.
2. Sample Collection
   A trained phlebotomist collects 3 ml of blood in a gel vacutainer from a vein in your arm.
3. Advanced Laboratory Testing
   The test is performed using Immunoturbidimetry in NABL and CAP-accredited Metropolis laboratories for accurate and reliable results.
4. Real-Time Tracking
   Track your sample and access reports via the Metropolis Healthcare app or website.
5. Report Delivery
   Reports are available within 6 hours and can be viewed online, by email, WhatsApp, or at your nearest Metropolis Lab.

Is Home Sample Collection Available for the C4 Blood Test?

Yes, Metropolis Healthcare offers home sample collection for the C4 Blood Test.
A certified phlebotomist collects your sample from home while maintaining sterile and temperature-controlled conditions.

How Long Does It Take to Get C4 Blood Test Results?

Reports are generally available within 6 hours of sample reaching the lab.
Note: Reporting time and cost may vary depending on your location.

Where Can You Access Your C4 Test Results?

You can view and download your reports:

• On the Metropolis Healthcare website
• Through the Metropolis Healthcare mobile app
• Via email or WhatsApp
• Or collect a printed copy from your nearest Metropolis Lab

Understanding C4 Blood Test Results

How to Prepare for the C4 Blood Test

To ensure accurate results:

• No fasting is required.
• Inform your doctor about any ongoing medications, supplements, or recent infections.
• Stay hydrated before your test.
• Provide complete clinical history for correct interpretation.

How is the C4 Test Performed?

• A blood sample is drawn from a vein in your arm.
• The sample is collected in a gel vacutainer and processed using Immunoturbidimetry.
• The method measures the amount of C4 protein in the serum.
• Results are compared with reference ranges to evaluate immune activity.

Factors That May Affect C4 Test Accuracy

• Acute infection or inflammation at the time of testing
• Use of immunosuppressive or anti-inflammatory medications
• Chronic liver disease affecting protein production
• Genetic complement deficiencies
• Laboratory handling or transport delays

Diseases Detected by C4 Blood Test

The C4 Blood Test helps in diagnosing and monitoring:

• Systemic Lupus Erythematosus (SLE)
• Rheumatoid Arthritis
• Glomerulonephritis
• Hereditary Angioedema
• Immune Complex Diseases
• Autoimmune Thyroiditis
• Sepsis or Chronic Infections