C5 Complement, Functional
Test Mnemonic
C5COMF
CPT Codes
- 86161 - QTY (1)
Aliases
- C5
- Complement
- Fifth Component of Complement
Includes
- C5 Complement, Functional, S
Performing Laboratory
Mayo Clinic Dpt of Lab Med & Pathology
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1 mL | Serum | SST (Gold) | Place specimen on ice after draw. | Frozen, Critical | Fasting preferred. Place tube on wet ice immediately after collection and allow specimen to clot. Separate serum from cells and transfer to standard aliquot tube. Freeze immediately. |
Alternate Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1 mL | Serum | No additive (Red) | Place specimen on ice after draw. | Frozen, Critical | Fasting preferred. Place tube on wet ice immediately after collection and allow specimen to clot. Separate serum from cells and transfer to standard aliquot tube. Freeze immediately. |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.5 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Frozen | 14 days |
| Ambient | Unacceptable |
| Refrigerated | Unacceptable |
Days Performed
Mon - Fri
Turnaround Time
2 - 4 days
Methodology
| Name | Description |
|---|---|
| Turbidimetry (TURB) |
Special Info
Grossly lipemic specimens are unacceptable.
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.