Doctor's Assessment Included
Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
C3 Complement
C3 Complement is particularly important for women with lupus, where serial monitoring helps predict and manage disease flares, especially kidney involvement.
What It Measures
This test measures the concentration of C3 protein in your blood. C3 is produced by the liver and is consumed during complement activation, making it both an inflammatory marker and indicator of complement pathway activity.
Why It Matters
Low C3 is particularly important in SLE monitoring, where falling complement levels often precede clinical flares. It also helps evaluate membranoproliferative glomerulonephritis and other immune complex diseases.
When to Test
Testing could be indicated for monitoring SLE disease activity, evaluating unexplained glomerulonephritis, assessing immune complex disorders, or investigating recurrent infections suggesting complement deficiency.
Symptoms
Low Levels
Low C3 may be associated with active lupus (especially nephritis), infections, liver disease, or hereditary complement deficiency. Symptoms depend on the underlying cause.
High Levels
Elevated C3 is typically seen as part of the acute-phase response during inflammation or infection. It is usually not clinically significant on its own.
Lifestyle Tips
If C3 is low due to autoimmune disease, adherence to prescribed treatment is essential. Regular monitoring helps detect disease flares early. Maintain overall health through a balanced diet and regular exercise.
Frequently Asked Questions
Why is C3 important in lupus?
Complement consumption in lupus causes C3 levels to drop, often before clinical symptoms worsen. Serial monitoring helps predict and manage flares.
What is the complement system?
A group of proteins that enhance the immune response by opsonising pathogens, recruiting immune cells, and directly lysing microorganisms.
Can C3 deficiency cause infections?
Yes. Inherited C3 deficiency predisposes to severe, recurrent bacterial infections because C3 is critical for opsonisation and pathogen clearance.