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Complement C4

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: Saturday, November 14, 2020 03:17:09 AM


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