Definition
What Complement C4a measures
C4a is a split product of the complement cascade. In CIRS workups it is used as a marker of innate-immune activation after biotoxin exposure.
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Innate immunityCompleteng/mL
Complement C4a
A complement split product that falsely rises if the tube sits
Illustrative sample band · Synthetic
1,200ng/mL
0Sample target 0–2,830 ng/mL3,056
Why it matters
How clinicians usually read it
The lab requires chilled EDTA plus a Futhan preservative and an immediate freeze. Room-temperature shipping activates complement in the tube and fabricates a high result. This cannot run on Tasso+.
When it reads low
A lower value can mean
A lower C4a is the quieter published pattern. It does not by itself rule out CIRS when other markers are loud.
When it reads high
A higher value can mean
A higher C4a can mark complement activation — or a delayed, unfrozen, or non-Futhan specimen. Handling comes before interpretation.
Questions for a clinician
Bring the number into a real conversation
01
Was Futhan added and the plasma frozen immediately?
02
If this is very high, do we repeat before treating the number?
03
How does C4a sit with TGF-β1, MMP-9, and VIP?
Educational boundary
Educational information only. Displayed ranges are illustrative sample bands, not a diagnosis, treatment plan, or substitute for the contracted laboratory report and a qualified clinician.
See it as a sample result
The sample dashboard shows an illustrative reading, target band, and trend for Complement C4a.