COMPLEMENT C<sub>4</sub> Mnemonic C4 Synonym C4 Guidelines Since specimen handling is critical to accuracy of test results, do not order on previously collected specimens (NO “ADD-ONS”). Specimen Collection Requirements Collect Serum, one 5.0 mL gold (SST) or 7.0 mL red top tube Handling Allow serum to clot completely at room temperature (minimum for SST: 30 minutes; minimum for red top tubes: 60 minutes). Centrifuge and remove serum from cells within 2 hours of collection. Refrigerate specimen within 2 hours of collection. If specimen will not arrive within testing lab within 24 hours of collection, freeze on dry ice or at -20°C. If additional testing is ordered, C4 must be submitted as a separate frozen aliquot from other testing. C4 and C3 can be submitted for testing together in a single aliquot with twice the volume. Preferred Volume 1.0 mL Serum Minimum Volume 0.5 mL Serum (1.2 mL minimum whole blood draw) Transport Preferred: Frozen (≤ -20°C) Also acceptable: Refrigerated (2-8°C), if specimen arrives in testing lab within 24 hours of collection and can be tested (or frozen) immediately upon arrival. Rejection Criteria Marked icteric, marked hemolyzed, moderate lipemic specimens, specimens that have undergone more than one freeze-thaw. No Add-On Requests. Stability FROM TIME OF COLLECTION: Room Temperature (18-26°C): 2 hours; Refrigerated (2-8°C): 24 hours; Frozen (≤ -20°C): 2 weeks (avoid repeated freeze/thaws cycles) Testing Information Performed Monday - Friday Reported 24-72 hours Method Nephelometry Reference Values Reference Values 16.3-47.8 mg/dL CPT Codes 86160 Last Updated: Thursday, January 5, 2017 03:42:04 AM