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Test Code C6 C6 Complement, Functional, Serum

Additional Codes

Mayo Test ID

Reporting Name

C6 Complement, Functional, S

Useful For

Diagnosis of C6 deficiency


Investigation of a patient with an undetectable total complement (CH50) level

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Serum Red

Specimen Required

Collection Container/Tube: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

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

2. Spin down and separate serum from clot.

3. Immediately freeze specimen.

Additional Information: Fasting preferred.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Red Frozen 14 days

Reference Values

32-57 U/mL

Day(s) and Time(s) Performed

Monday through Saturday; Continuous with a 3 p.m. cutoff

Test Classification

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

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
C6FX C6 Complement, Functional, S 60459-5


Result ID Test Result Name Result LOINC Value
C6FX C6 Complement, Functional, S 60459-5

Clinical Information

Complement proteins are components of the innate immune system. There are 3 pathways to complement activation: 1) the classic pathway, 2) the alternative (or properdin) pathway, and 3) the lectin activation (mannan-binding protein [MBP]) pathway. The classic pathway of the complement system is composed of a series of proteins that are activated in response to the presence of immune complexes. The activation process results in the generation of peptides that are chemotactic for neutrophils and that bind to immune complexes and complement receptors. The end result of the complement activation cascade is the formation of the lytic membrane attack complex (MAC).


Patients with deficiencies of the late complement proteins (C5, C6, C7, C8, and C9) are unable to form the MAC, and may have increased susceptibility to neisserial infections.


A number of patients with C6 deficiency have been reported, and the majority of these patients are South African. Most of these patients have systemic meningococcal infection and some have had invasive gonococcal infections. Normal levels of C6 antigen have been reported in patients with dysfunctional C6 lytic activity.

Analytic Time

Same day/1 day

NY State Approved


Method Name

Automated Liposome Lysis Assay

Northwell Health Laboratories Additional Information:

Computer Interface Code

   PDM # 5902190