C9 Complement, Functional
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C9 Complement – Functional (C9FX), Serum
Test ID: C9FX S
Test
Method
Automated Liposome Lysis Assay
Method Description
Complement 9 (C9) activity is measured by mixing patient serum with a C9-deficient serum. The lytic activity of the serum mixture is tested against sensitized, labeled liposomes. If lysis occurs, the patient serum must be the source of the C9. The target liposomes are a commercial reagent (WAKO total complement CH50).
Platform
Advia XPT
Report Includes
Specimens
Serum
Clinical Utility
Diagnosis of C9 deficiency. Investigation of a patient with a low total (hemolytic) complement level.
Test Version
11-Nov-2025
Specimen
Specimens
Serum
Collection Containers
Preferred
Gold top (clot activator & gel)
Acceptable
Red top (no additive)
Sample Volume
1.0 mL
Minimum Volume
0.5 mL
Patient Preparation
Fasting 12 hours, preferred but not required
Collection & Handling
Handling Information
1. Immediately after specimen collection, place the tube on wet ice and allow specimen to clot.
2. Centrifuge at 4 degrees C and aliquot serum into a plastic vial.
3. Within 30 minutes of centrifugation, freeze specimen. Specimen must be placed on dry ice if not frozen immediately.
NOTE: If a refrigerated centrifuge is not available, it is acceptable to use a room temperature centrifuge, provided the sample is kept on ice before centrifugation, and immediately afterward, the serum is aliquoted and frozen.
Stability
| Frozen | 14 days |
|---|
Rejection Criteria
| Lipemia | Gross |
|---|
Test Version
11-Nov-2025
Performance / Interpretation
Method
Automated Liposome Lysis Assay
Method Description
Complement 9 (C9) activity is measured by mixing patient serum with a C9-deficient serum. The lytic activity of the serum mixture is tested against sensitized, labeled liposomes. If lysis occurs, the patient serum must be the source of the C9. The target liposomes are a commercial reagent (WAKO total complement CH50).
Platform
Advia XPT
Turnaround Time
8 days
Results
| Name | Units | Reference Range | Conversion Factor | |
|---|---|---|---|---|
| C9 Complement, Functional | U/mL |
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Low levels of complement may be due to inherited deficiencies, acquired deficiencies, or due to complement consumption (eg, as a consequence of infectious or autoimmune processes).
Absent C9 levels in the presence of normal C3 and C4 values are consistent with a C9 deficiency. Absent C9 levels in the presence of low C3 and C4 values suggests complement consumption. Normal results indicate both normal C9 protein levels and normal functional activity. As with all complement assays, proper specimen handling is of utmost importance to ensure that the complement system is not activated before clinical testing. Absent (or low) C9 functional levels in the presence of normal C9 antigen levels should be replicated with a new serum specimen to confirm that C9 inactivation did not occur during shipping. |
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Test Version
11-Nov-2025
Interface / Setup
HL7 Interface Codes
| Order Code | Result Codes | Units |
|---|---|---|
| C9FX S | 63666C9 Complement, Functional, S | U/mL |
Test Version
11-Nov-2025