Complement C1q
The Complement C1q test measures a key protein of the immune complement system. It is used to investigate immune dysfunction and autoimmune conditions.
Turnaround time
1 week
Biomarkers count
1
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Details about Complement C1q
What is the Complement C1q test?
The Complement C1q test measures the level of Complement Component 1q, a protein that initiates the classical complement pathway. The complement system is part of the innate immune response and plays a critical role in identifying and clearing pathogens and immune complexes.
C1q binds to antibodies attached to antigens, triggering a cascade of immune activation that helps eliminate infections and regulate inflammation. Adequate C1q levels are essential for effective immune surveillance and immune complex clearance.
This test is commonly used in immunology and rheumatology when investigating autoimmune disease, immune complex disorders, or suspected complement deficiencies.
Why do I need a Complement C1q test?
Abnormal C1q levels can be associated with autoimmune diseases, immune complex–mediated conditions, or rare inherited complement deficiencies. Testing helps clarify whether the classical complement pathway is functioning normally.
You may need a Complement C1q test if you:
- Have suspected autoimmune disease
- Have recurrent or severe infections
- Have unexplained inflammation
- Have low complement levels on other tests
- Are being investigated for lupus or related conditions
- Have symptoms suggesting immune complex disease
- Require detailed immune system assessment
Symptoms that may prompt testing include:
- Persistent fatigue
- Joint pain or swelling
- Skin rashes
- Recurrent infections
- Unexplained inflammatory symptoms
Benefits of the Complement C1q test
- Assesses classical complement pathway function
Evaluates a key immune activation step. - Supports autoimmune disease investigation
Relevant in immune complex disorders. - Useful in recurrent infection assessment
Helps identify complement-related immune issues. - Clinically recognised immune marker
Used in specialist immunology testing. - Supports diagnosis of rare complement deficiencies
Identifies abnormal complement activity. - Simple blood test
Requires only a single blood sample. - Guides further immune investigations
Helps determine need for additional complement testing. - Improves diagnostic clarity
Aids understanding of immune dysfunction.
Step by step – how the test works
You can access Complement C1q testing UK-wide through two options:
- Clinic appointment
Choose your nearest UK clinic, where a healthcare professional will take your blood sample. - At-home or hotel visit (£60 extra)
A qualified phlebotomist visits your home or hotel, so you don’t need to travel.
Your sample is analysed in an accredited UK laboratory, and results are delivered securely.
Your results explained
Low Complement C1q levels
May indicate complement deficiency or consumption due to immune complex activity, often seen in autoimmune conditions.
Typical UK interpretation:
- Below laboratory reference range
Normal Complement C1q levels
Suggest intact classical complement pathway function.
Typical UK interpretation:
- Within laboratory reference range
High Complement C1q levels
May be associated with acute inflammation or immune activation.
Typical UK interpretation:
- Above laboratory reference range
Reference ranges vary between laboratories and must be interpreted clinically.
How It Works
Simple steps to get your results
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Visit or Test at Home
Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
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WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.