Inflammation / Immune

Complement C4

Unit: mg/dLID: I008

What This Test Measures

Immune system protein; part of complement cascade

Conventional vs. Functional Optimal Range

Conventional "Normal"

10-40 mg/dL

Your doctor says you're "fine" anywhere in this range

Functional Optimal

15-35 mg/dL

This is where you actually feel great

The gap between these ranges is why you feel terrible with "normal" labs. Conventional medicine waits for disease. Functional medicine optimizes for health.

Gabriel's Take

C4 parallels C3. Low C3 + low C4 = autoimmune disease (lupus, vasculitis). Low C4 alone = hereditary angioedema. Should be mid-range (15-35). Functional medicine checks complement in autoimmune workups.