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HelpTest Code C4 Func C4 Complement, Functional, Serum
Reporting Name
C4 Complement, Functional, SClinical System Name: C4 Complement, Functional
Useful For
Diagnosis of C4 deficiency
Investigation of a patient with an undetectable total complement level
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumOrdering Guidance
The total complement assay (COM / Complement, Total, Serum) should be used as a screen for suspected complement deficiencies before ordering individual complement component assays. A deficiency of an individual component of the complement cascade will result in an undetectable total complement level.
Specimen Required
Patient Preparation: Fasting preferred but not required
Supplies: Sarstedt Aliquot Tube 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Immediately after specimen collection, place the tube on wet ice and allow specimen to clot.
2. Centrifuge at 4° 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 specimen is kept on ice before centrifugation, and immediately afterward, the serum is aliquoted and frozen.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen | 14 days |
Reference Values
22-45 U/mL
Day(s) Performed
Monday through Friday
TAT: 3 - 5 days
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
86161
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| C4FX | C4 Complement, Functional, S | 93978-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| C4FX | C4 Complement, Functional, S | 93978-5 |
Method Description
Activity of C4 is measured by mixing patient serum with a C4-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 C4. The target liposomes are a commercial reagent (WAKO total complement CH50), and the assay is performed on an Advia XPT.(Unpublished Mayo method)
Report Available
1 to 3 daysReject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Method Name
Automated Liposome Lysis Assay