C5 Complement, Functional




Test Mnemonic

C5COMF

CPT Codes

  • 86161 - QTY (1)

Aliases

  • C5
  • Complement
  • Fifth Component of Complement

Performing Laboratory

Mayo Clinic Dpt of Lab Med & Pathology


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
1 mLSerumNo additive (Red) FrozenImmediately after specimen collection, place the tube on wet ice. Spin down and separate serum from clot. Immediately freeze specimen.

Minimum Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
0.5 mL     

Stability

Environmental Condition Description
Frozen14 days
AmbientUnacceptable
RefrigeratedUnacceptable

Days Performed

Mon - Sat

Turnaround Time

3 days

Methodology

Name Description
Turbidimetry (TURB) 

Reference Range

C5 Complement, Functional
Sex Age From Age To Type Range Range Unit
       29 - 53 U/mL 

Special Info

Immediately after specimen collection, place the tube on wet ice. Spin down and separate serum from clot. Immediately freeze specimen.

Clinical Info

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. More than 30 cases of C5 deficiency have been reported. Most of these patients have neisserial infections. Complement levels can be detected by antigen assays that quantitate the amount of the protein (C5AG/ C5 Complement, Antigen, Serum). For most of the complement proteins, a small number of cases have been described in which the protein is present but is nonfunctional. These rare cases require a functional assay to detect the deficiency.