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HelpTest Code LAB4232/6842/C1ESR C1 Esterase Inhibitor Antigen, Serum
Additional Codes
Mayo Code: C1ES
Specimen Required
Patient Preparations: Fasting preferred but not required.
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Immediately after specimen collection, place the tube on wet ice.
2. Centrifuge and aliquot serum into plastic vial.
3. Freeze specimen within 30 minutes.
Method Name
Nephelometry
Reporting Name
C1 Esterase Inhibitor Antigen, SSpecimen Type
SerumReject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Day(s) and Time(s) Performed
Monday through Friday; Continuously until 3 p.m.
Analytic Time
1 dayPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved or is exempt by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
83883
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| C1ES | C1 Esterase Inhibitor Antigen, S | 4477-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| C1ES | C1 Esterase Inhibitor Antigen, S | 4477-6 |
Secondary ID
8198Useful For
Diagnosis of hereditary angioedema
Monitoring levels of C1 esterase inhibitor in response to therapy
Clinical Information
C1 esterase inhibitor blocks the activation of C1 (first component of the complement cascade) to its active form. The deficiency of C1 esterase inhibitor results in the inappropriate activation of C1 and the subsequent release of an activation peptide from C2 with kinin-like activity. This kinin-like peptide enhances vascular permeability. C1 esterase inhibitor deficiency results in hereditary or acquired angioedema. This disease is an autosomal dominant inherited condition, in which exhaustion of the abnormally low levels of C1 esterase inhibitor results in C1 activation, breakdown of C2 and C4, and subsequent acute edema of subcutaneous tissue, the gastrointestinal tract, or the upper respiratory tract. The disease responds to attenuated androgens.
Because 15% of C1 inhibitor deficiencies have nonfunctional protein, some patients will have abnormal functional results (FC1EQ / C1 Esterase Inhibitor, Functional Assay, Serum) in the presence of normal (or elevated) antigen levels.
Interpretation
Abnormally low results are consistent with a heterozygous C1 esterase inhibitor deficiency and hereditary angioedema.
Fifteen percent of hereditary angioedema patients have a normal or elevated level but nonfunctional C1 esterase inhibitor protein. Detection of these patients requires a functional measurement of C1 esterase inhibitor; FC1EQ / C1 Esterase Inhibitor, Functional Assay, Serum.
Measurement of C1q antigen levels; C1Q / Complement C1q, Serum, is key to the differential diagnoses of acquired or hereditary angioedema. Those patients with the hereditary form of the disease will have normal levels of C1q, while those with the acquired form of the disease will have low levels.
Studies in children show that adult levels of C1 inhibitor are reached by 6 months of age.
Cautions
Quantitation of specific proteins by nephelometric means may not be possible in lipemic sera due to the extreme light scattering properties of the specimen. Turbidity and particles in the specimen may result in extraneous light scattering signals, resulting in variable specimen analysis.
Clinical Reference
1. Frank MM: Complement deficiencies. Pediatr Clin North Am. 2000;47(6):1339-1354
2. Gelfand JA, Boss GR, Conley CL, et al: Acquired C1 esterase inhibitor deficiency and angioedema: a review. Medicine. 1979;58(4):321-328
3. Rosen FS, Alper CA, Pensky J, et al: Genetically determined heterogeneity of the C1 esterase inhibitor in patients with hereditary angioneurotic edema. J Clin Invest. 1971;50(10):2143-2149
4. Frigas E: Angioedema with acquired deficiency of the C1 inhibitor: a constellation of syndromes. Mayo Clin Proc. 1989;64:1269-1275
5. Soldin SJ, Hicks JM, Bailey J, et al: Pediatric reference ranges for estradiol and C1 esterase inhibitor. Clin Chem. 1998;44(6s):A17
Method Description
C1 esterase inhibitor complement antigen (C1ES) is measured by immunonephelometry. Antiserum to C1ES is mixed with patient serum, the light scatter resulting from the antibody interaction with C1ES is measured, and the signal is compared to standard concentrations of C1ES.(Instruction Manual: Siemens Nephelometer II Operations. Siemens, Inc; Version 2.3, 2008; Addendum to the Instruction Manual 2.3, 08/2017)
Specimen Retention Time
14 daysSpecimen Minimum Volume
0.5 mL
Reference Values
19-37 mg/dL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen (preferred) | 28 days | |
| Refrigerated | 28 days | ||
| Ambient | 72 hours |