High Complement C4: what it means
A Complement C4 result above the normal range is considered high. Here is what a raised Complement C4 can point to, and when it is worth discussing with a doctor.
Reference range: ~10–40 mg/dL; a LOW level (consumption) is meaningful in lupus activity, and a persistently low C4 is a clue to hereditary angioedema
Understand your full resultWhat a high Complement C4 can mean
- Inflammation / infection — C4 is an acute-phase protein and can rise non-specifically.
- Not usually the clinically important direction — a high C4 is rarely the point of the test.
When to discuss with a doctor
C4 is interpreted alongside C3 and the autoimmune markers, not alone. In lupus, a falling C4 (with C3) can accompany or precede a flare, especially in the kidneys, and is used to monitor disease activity. Separately, in someone with recurrent unexplained episodes of deep swelling (of the face, limbs, gut or airway) that don't respond to allergy treatment, a persistently low C4 is an important clue that prompts testing for hereditary angioedema — a condition that is managed very differently from ordinary allergic swelling. Mediora.AI shows C4 with C3, ANA and anti-dsDNA so the pattern is read together; the interpretation belongs with rheumatology or immunology.
Conditions this can relate to
Keep reading
One value is a snapshot. Upload the full test to see every marker explained together.
Upload your test - freeMediora.AI is informational - interpretation, not a diagnosis. A single out-of-range value is common and often benign; always discuss decisions with your doctor.