Ordering Recommendation

Follow-up test for complement activity screening when CH50 is low or absent and AH50 is normal and high suspicion remains for complement deficiency.

Mnemonic
C2
Methodology

Quantitative Radial Immunodiffusion

Performed

Mon, Thu

Reported

5-10 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Collect

Serum separator tube.

Specimen Preparation

Allow specimen to clot for one hour at room temperature. Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube and freeze immediately. (Min: 0.3 mL)

Storage/Transport Temperature

CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered.

Unacceptable Conditions

Non-frozen specimens. Specimens exposed to repeated freeze/thaw cycles. Specimens left to clot at refrigerated temperature.

Remarks
Stability

After separation from cells: Ambient: 2 hours; Refrigerated: Unacceptable; Frozen: 2 weeks

Reference Interval

Effective May 21, 2018
1.6-4.0 mg/dL

Interpretive Data

Decreased C2 levels may be associated with increased susceptibility to infection (especially pneumococcal infections), systemic lupus erythematosus-like disease, rashes, arthritis, nephritis, and with C1-Esterase deficiency.  Increased C2 levels are associated with the acute phase response.

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

86160

Components
Component Test Code* Component Chart Name LOINC
0050148 Complement Component 2 4484-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • C2
  • C2 Antigen
  • C2 Level
  • Classical Pathway - Complement
  • complement classical pathway
  • Second componenet of complement
Complement Component 2