SC5b-9 Level Terminal Complement Complex, Plasma
Use
The test is used for detecting increased complement activation, specifically by measuring the soluble C5b-9 (sC5b-9) complex. This measurement serves as a surrogate marker for terminal complement activation via classical, lectin, or alternative pathways. Elevated concentrations of C5b-9 are associated with the development of transplant-associated thrombotic microangiopathy (TA-TMA), a complication of hematopoietic stem cell transplant, and may also be found in other conditions where complement activation occurs, such as immune-complex disease, infection, atypical hemolytic uremic syndrome, and C3 glomerulopathies.
Special Instructions
Proper specimen handling is critical to ensure the complement system is not activated before clinical testing. It's ideal to perform the measurement of soluble C5b-9 prior to treatment initiation and in the absence of therapy with complement inhibitors like eculizumab and ravulizumab.
Limitations
The test shows very high sensitivity for TA-TMA but modest specificity (40%-50%). Increased sC5b-9 concentrations might be found in various other transplant complications and conditions where there is complement activation. Therefore, panel testing such as AHUSD may provide more comprehensive diagnostic information.
New York Approved
Methodology
Immunoassay (ELISA)
Biomarkers
LOINC Codes
- 93244-2
- 93244-2
Result Turnaround Time
3-5 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1.5 mL
Minimum Volume
0.75 mL
Container
Plastic vial
Collection Instructions
Immediately after specimen collection, place the tube on wet ice. Centrifuge between 1000 and 2000 x g for 10 minutes at 4 degrees C and aliquot plasma into a plastic vial. Within 30 minutes of centrifugation, freeze the specimen. Specimen must be placed on dry ice if not frozen immediately.
Patient Preparation
Fasting for 8 hours is preferred but not required. Do not collect specimens for at least 48 hours following plasma exchange.
Causes for Rejection
Gross hemolysis, lipemia, and icterus are acceptable.
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |