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Test Code C2FXN C2 Complement, Functional, Serum

Important Note

  • MUST be drawn at the Outpatient Lab at the Main Campus
  • MUST be sent on ICE

Reporting Name

C2 Complement, Functional, S, NR

Useful For

Investigation of a patient with a low (absent) hemolytic complement

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum Red


Ordering Guidance


The total complement assay (COM / Complement, Total, Serum) should be used as a screen for suspected complement deficiencies before ordering individual complement component assays. A deficiency of an individual component of the complement cascade will result in an undetectable total complement level.

 

To evaluate for complement C2, C3, and C4 in one orderable, consider ordering C2 / C2 Complement, Functional, with Reflex, Serum.



Specimen Required


Patient Preparation: Fasting preferred but not required

Supplies: Sarstedt 5 mL Aliquot Tube (T914)

Collection Container/Tube: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Immediately after specimen collection, place the tube on wet ice.

2. Centrifuge and aliquot serum into plastic vial.

3. Immediately freeze specimen.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Frozen 21 days

Reference Values

25-47 U/mL

Day(s) Performed

Monday through Friday

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

86161

LOINC Code Information

Test ID Test Order Name Order LOINC Value
C2FXN C2 Complement, Functional, S, NR 93977-7

 

Result ID Test Result Name Result LOINC Value
C2FX C2 Complement,Functional,S 93977-7
INT53 Interpretation 69048-7

Interpretation

Low levels of complement may be due to inherited deficiencies, acquired deficiencies, or due to complement consumption (eg, as a consequence of infectious or autoimmune processes).

 

Absent (or low) C2 levels in the presence of normal C3 and C4 values are consistent with a C2 deficiency.

 

Low C2 levels in the presence of low C3 and C4 values are consistent with a complement-consumptive process.

 

Low C2 and C4 values, in the presence of normal values for C3 is suggestive of C1 esterase inhibitor deficiency.

Clinical Reference

1. Gaither TA, Frank MM: Complement. In: Henry JB, ed. Clinical Diagnosis and Management by Laboratory Methods. 17th ed. WB Saunders Company; 1984:879-892

2. Agnello V: Complement deficiency states. Medicine. 1978;57:1-23

3. Buckley D, Barnes L: Childhood subacute cutaneous lupus erythematosus associated with homozygous complement 2 deficiency. Pediatr Dermatol. 1995;12:327-330

4. Willrich MAV, Braun KMP, Moyer AM, Jeffrey DH, Frazer-Abel A. Complement testing in the clinical laboratory. Crit Rev Clin Lab Sci. 2021 Nov;58(7):447-478. doi: 10.1080/10408363.2021.1907297

Report Available

1 to 3 days

Method Name

Automated Liposome Lysis Assay