Lab test

Complement C4 Level

Complement C4 Level Test measures C4 protein levels in the blood to assess immune system activity and detect autoimmune disorders.
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NABL-certified lab Free home collection Report in 24 hrs
ReportWithin 24 hrs
SampleBlood
CollectionHome or centre
FastingNot needed
How it works
1
Book in a minute
Add to cart, pick a date and time slot, pay online or at collection.
2
Sample collected at home or centre
A trained phlebotomist arrives in your slot with sealed, single-use kits.
3
Report on WhatsApp
Within 24 hours on WhatsApp and under My Orders.
Preparation
No special preparation needed unless your doctor advises otherwise.
About this test
Complement C4 Level Test measures C4 protein levels in the blood to assess immune system activity and detect autoimmune disorders.
COMPLEMENT C4 LEVEL This test is a blood test used to measure the level of complement component C4, an important protein of the immune system. C4 plays a key role in immune response and inflammation.

The purpose of this test is to:

  • Measure C4 protein levels in the blood
  • Assess immune system function
  • Help diagnose autoimmune diseases such as lupus
  • Evaluate inflammatory and infectious conditions
  • Monitor disease activity and treatment response

COMPLEMENT C4 LEVEL Test Purpose

The Complement C4 Level Test measures the amount of Complement Component 4 (C4), an important protein in the complement system that plays a key role in the body's immune response. C4 helps the immune system identify and eliminate bacteria, viruses, and other harmful microorganisms while also supporting the removal of damaged cells and immune complexes. Measuring C4 levels provides valuable information about immune system activity and helps identify abnormalities associated with autoimmune and inflammatory conditions.

This test is commonly used alongside the Complement C3 Test and other laboratory investigations to diagnose and monitor autoimmune diseases such as Systemic Lupus Erythematosus (SLE), rheumatoid arthritis, vasculitis, and certain kidney disorders. Low C4 levels may indicate increased complement consumption due to active autoimmune disease, hereditary angioedema, or chronic infections, while elevated levels may occur in some inflammatory conditions. Healthcare providers may also recommend this test to monitor disease activity, evaluate treatment response, and investigate recurrent infections or unexplained inflammation. The results should always be interpreted along with clinical symptoms, medical history, and other diagnostic tests for a comprehensive assessment.

COMPLEMENT C4 LEVEL TEST is Recommended for Individuals:

  • Individuals with symptoms suggestive of autoimmune diseases such as lupus or rheumatoid arthritis.
  • Patients being evaluated for Systemic Lupus Erythematosus (SLE) or other connective tissue disorders.
  • People with recurrent episodes of unexplained swelling suggestive of hereditary angioedema.
  • Individuals with persistent inflammation or unexplained kidney disease.
  • Patients undergoing monitoring for autoimmune disease activity or treatment response.
  • Individuals with recurrent infections or suspected complement system disorders.

FAQs

1. What is the Complement C4 Level Test used for?
The Complement C4 Level Test measures the amount of C4 protein in the blood to evaluate immune system function. It helps diagnose and monitor autoimmune diseases, inflammatory conditions, hereditary angioedema, and certain kidney disorders.

2. Do I need to fast before the Complement C4 Level Test?
No. Fasting is generally not required before the Complement C4 Level Test. However, you should follow any specific instructions provided by your healthcare provider or diagnostic laboratory.

3. What does a low Complement C4 level indicate?
A low C4 level may be associated with autoimmune diseases such as lupus, hereditary angioedema, chronic infections, or increased complement consumption due to ongoing immune system activity. Your doctor will interpret the results along with other clinical findings and laboratory tests.

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Questions people ask
How soon will I get my report?
Your report is delivered within 24 hours of sample collection — on WhatsApp and under My Orders.
Is home sample collection available?
Yes. A trained phlebotomist visits your home with sealed, single-use kits. Home collection is free.
Do I need to fast or prepare?
No fasting is required for this test unless your doctor advises otherwise.
How do I pay?
Pay online (UPI / cards) or pay at collection or at the centre. The price you see is what you pay — it includes the report, with no hidden charges.
Is the lab accredited?
Yes. Prima Diagnostics runs NABL-certified labs with strict quality control across 7 centres in Bengaluru.