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HelpTest Code C1QFX C1q Complement, Functional, Serum
Reporting Name
C1Q Complement, Functional, SUseful For
Diagnosis of C1 deficiency
Investigation of a patient with an absent 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
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. Sample 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 aliquoted and frozen.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen | 14 days |
Reference Values
34-63 U/mL
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
86161
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| C1QFX | C1Q Complement, Functional, S | 87722-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| C1QFX | C1Q Complement, Functional, S | 87722-5 |
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).
The measurement of C1q activity is an indicator of the amount of C1 present. Absent C1q levels in the presence of normal C3 and C4 values are consistent with a C1 deficiency. Low C1q levels in the presence of low C4 but normal C3 may indicate the presence of an acquired inhibitor (autoantibody) to C1 esterase inhibitor.
Clinical Reference
1. Sonntag J, Brandenburg U, Polzehl D, et al. Complement systems 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, et al. IFCC-standardization 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, ed. Clinical Diagnosis and Management by Laboratory Methods. 17th ed. WB Saunders Company: 1984:879-892
5. O'Neil KM. Complement deficiency. Clin Rev Allergy Immunol. 2000;19:83-108
6. Frank MM. Complement deficiencies. Pediatr Clin North Am. 2000;47(6):1339-1354
7. Brodszki N, Frazer-Abel A, Grumach AS, et al. European Society for Immunodeficiencies (ESID) and European Reference Network on Rare Primary Immunodeficiency, Autoinflammatory and Autoimmune Diseases (ERN RITA) Complement Guideline: Deficiencies, diagnosis, and management. J Clin Immunol. 2020;40(4):576-591
8. Willrich MAV, Braun KMP, Moyer AM, Jeffrey DH, Frazer-Abel A. Complement testing in the clinical laboratory. Crit Rev Clin Lab Sci. 2021;58(7):447-478. doi:10.1080/10408363.2021.1907297
Report Available
1 to 3 daysMethod Name
Automated Liposome Lysis Assay