Complement C5, Concentration
Also known as: C5
Use
This test is utilized as a follow-up for complement activity screening when CH50 and AH50 are low or absent. It helps to identify cases with a high suspicion of complement deficiency. Low concentration of C5 may suggest inherited or acquired deficiencies, or a secondary consumption process from liver synthesis incapability. Low C5 concentration alongside low C3 and C4 concentrations suggests secondary consumption, while normal C3 and C4 indicate a C5 deficiency.
Special Instructions
The specimen must be handled promptly; Serum should clot for one hour at room temperature, then serum should be separated and transferred to an ARUP Standard Transport Tube to be frozen immediately. It is critical to submit separate specimens if multiple tests are ordered.
Limitations
The test primarily measures the concentration of Complement C5 and may not fully reflect the functional activity of C5 proteins. In cases where the C5 complement protein is nonfunctional yet present, additional testing for C5 functional activity is recommended. Non-frozen specimens or those exposed to repeated freeze/thaw cycles are unacceptable. Clotted specimens left at refrigerated temperature are also unsuitable.
New York Approved
Methodology
Immunoassay (Quantitative Radial Immunodiffusion)
Biomarkers
LOINC Codes
- 4505-4
Result Turnaround Time
3-8 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.3 mL
Container
ARUP Standard Transport Tube
Collection Instructions
Allow specimen to clot for one hour at room temperature. Separate serum from cells ASAP or within 2 hours of collection. Transfer serum to an ARUP Standard Transport Tube and freeze immediately.
Storage Instructions
Store and transport frozen. Stability: Ambient for 2 hours; Refrigerated unacceptable; Frozen for 2 weeks.
Causes for Rejection
Non-frozen specimens. Specimens exposed to repeated freeze/thaw cycles. Specimens left to clot at refrigerated temperature.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 2 hours |
| Refrigerated | Unacceptable |
| Frozen | 2 weeks |