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Complement Component C4a, Plasma
Test Code13555
CPT Codes
86160
Preferred Specimen
2 mL plasma collected in an EDTA (lavender-top) tube submitted in a protease inhibitor transport tube
Minimum Volume
1 mL
Instructions
Collect whole blood into EDTA (lavender-top) tube.
Centrifuge and pour 1-2 mL plasma carefully into protease inhibitor transport tube. (Note gradations on side of tube.) Freeze and transport on dry ice (preferred) or place into refrigerated cold pack container.
Centrifuge and pour 1-2 mL plasma carefully into protease inhibitor transport tube. (Note gradations on side of tube.) Freeze and transport on dry ice (preferred) or place into refrigerated cold pack container.
Transport Container
Protease inhibitor transport tube
Transport Temperature
Frozen
Specimen Stability
Room temperature: Unacceptable
Refrigerated: 7 days
Frozen -20° C: 21 days
Frozen -70° C: 60 days
Refrigerated: 7 days
Frozen -20° C: 21 days
Frozen -70° C: 60 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Gross hemolysis • Grossly lipemic • Specimen not shipped in Protease Inhibitor transport tube • Grossly icteric
Methodology
Enzyme Linked Immunosorbent Assay (ELISA)
FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
Setup Schedule
Set up: Mon, Wed, Sat; Report available: 2-4 days
Reference Range
≤1028 ng/mL
Clinical Significance
During activation of the classical or lectin pathway of complement, C4 is cleaved into C4a and C4b. C4a is rapidly cleaved to the more stable form C4a-des-arg. Even if total C3 and C4 levels are not low (because of increased production by the liver during acute inflammation), elevated levels of C4a-des-arg indicate recent complement pathway activation.
