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Test Code
C4A
Test Name
Complement Component Level 4A
CPT Codes
86160
Expected Turnaround Time
3 - 6 days
Clinical Utility

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.
Specimen and Container Info

Specimen Type: Plasma

Collection Container: Protease Inhibitor Futhan Kit

Desired Specimen Volume: 2 mL
Collection Instructions
  1. Collect a lavender top (EDTA) tube via venipuncture.
Processing and Submission Instructions
  1. Separate plasma from cells.
  2. Transfer 1-2 mL of plasma carefully into the protease inhibitor transport tube. (Note gradations on side of tube.)
  3. Freeze immediately and maintain frozen.
Transport Instructions

Transport to the laboratory frozen. 
Stability Requirements

Frozen

Frozen -20° C: 21 days

Frozen -70° C: 60 days
Causes for Rejection
  • Gross hemolysis
  • Grossly lipemic
  • Grossly icteric
  • Specimen not shipped in Protease Inhibitor transport tube
Methodology
ELISA
Reference Intervals

 See patient report.
Alternate Names
  • C4a des Arg
  • C4a complement
  • Activation Complement C4a
Reference Lab
Quest Diagnostics Nichols Institute
Testing Schedule
Routine, 3 times per week
The American Medical Association (AMA) Current Procedural Terminology (CPT) codes published by HNL Lab Medicine are guidelines and are intended for informational purposes only. CPT coding is the exclusive responsibility of the billing entity. View the Terms.
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