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HelpTest Code C5AG C5 Complement, Antigen, Serum
Reporting Name
C5 Complement, Antigen, SUseful For
Diagnosis of C5 deficiency
Investigation of a patient with an absent total complement (CH50) 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 for 12 hours is preferred but not required.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Frozen (preferred) | 60 days |
| Refrigerated | 28 days | |
| Ambient | 7 days |
Reference Values
10.6-26.3 mg/dL
Day(s) Performed
Monday through Friday
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
86160
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| C5AG | C5 Complement, Antigen, S | 4505-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| C5AG | C5 Complement, Antigen, S | 4505-4 |
Interpretation
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 C5 levels in the presence of normal C3 and C4 values are consistent with a C5 deficiency. Absent C5 levels in the presence of low C3 and C4 values suggest complement consumption.
A small number of cases have been described in which the complement protein is present but is nonfunctional. These rare cases require a functional assay to detect the deficiency; for more information see C5FX / C5 Complement, Functional, Serum.
Clinical Reference
1. Sonntag J, Brandenburg U, Polzehl D, et al. Complement system in healthy term newborns: reference values in umbilical cord blood. Pediatr Dev Pathol. 1998;1(2):131-135
2. Prellner K, Sjoholm AG, Truedsson L. Concentrations of C1q, factor B, factor D and properdin in healthy children, and the age-related presence of circulating C1r-C1s complexes. Acta Paediatr Scand. 1987;76(6):939-943
3. Davis ML, Austin C, Messmer BL, Nichols WK, Bonin AP, Bennett MJ. IFCC-standardized pediatric reference intervals for 10 serum proteins using the Beckman Array 360 system. Clin Biochem. 1996;29(5):489-492
4. Gaither TA, Frank MM. Complement. In: Henry JB. Clinical Diagnosis and Management by Laboratory Methods. 17th ed. Saunders; 1984:879-892
5. O'Neil KM. Complement deficiency. Clin Rev Allergy Immunol. 2000;19(2):83-108
6. Frank MM. Complement deficiencies. Pediatr Clin North Am. 2000;47(6):1339-1354
7. Volokhina EB, van de Kar NC, Bergseth G, et al. Sensitive, reliable and easy-performed laboratory monitoring of eculizumab therapy in atypical hemolytic uremic syndrome. Clin Immunol. 2015;160(2):237-243.
8Andreguetto B, Murray D, Snyder M, Tostrud L, Willrich MA. Abstract 003: The impact of eculizumab in complement assays. Mol Immunol. 2015;67:119-120. doi:10.1016/j.molimm.2015.03.013
Report Available
2 to 5 daysMethod Name
Nephelometry