Lab Dept:


Test Name:

C2 Function

General Information

Lab Order Codes:



C2 Complement Component, Function, S; C2 (Second Component of Complement), Functional, Serum; C2

CPT Codes:

86161 – Complement; functional activity, each component

Test Includes:

C2 Function Complement Component reported in U/mL.


Test Indications:

Useful for the investigation of a patient with a low (absent) hemolytic complement (CH50).

Lab Testing Sections:

Chemistry - Sendouts

Referred to:

Mayo Medical Laboratories (MML Test: 81835/C2)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

1 - 2 days, test set up Monday - Saturday

Special Instructions:

See Patient Preparation


Specimen Type:



Red top tube

Draw Volume:

3 mL (Minimum: 1.5 mL) blood

Processed Volume:

1 mL (Minimum: 0.5 mL) serum


Routine venipuncture


Special Processing:

Lab Staff: Centrifuge specimen, remove serum aliquot from clot and place in a plastic vial. Store and ship at frozen temperatures. Forward promptly.

Patient Preparation:

Patient should be fasting

Sample Rejection:

Specimens other than serum; warm specimens; lipemia; mislabeled or unlabeled specimens


Reference Range:

25 - 47 U/mL

Critical Values:



Absent (or low) C2 functional levels in the presence of normal C2 antigen levels should be replicated with a new serum specimen to confirm that C2 inactivation has not occurred during shipping.

If requested not to reflex low C2 result specimens for C3 and C4 testing, the following comment will be reported; “C2 result is decreased. This could be a result of an inherited C2 deficiency, complement consumption or C1 esterase inhibitor or deficiency. Analysis of C3 and C4 would be required for further interpretation.”


C2H50 Automated Liposome Lysis Assay


Mayo Medical Laboratories Web Page (April 2011)


5/22/2008: Removed reflex for below reference range C2 results to C3 and C4 with custom Mayo coding. Children’s performs these internally.