Home
HelpTest Code INPT411 C1 Esterase Inhibitor Antigen, Serum
Additional Codes
YC1E
Included in C1 Esterase Inhib (Qual & Funct) Panel- orderable procedure code YC1NH
Reporting Name
C1 Esterase Inhibitor Antigen, SUseful For
Diagnosis of hereditary angioedema
Monitoring levels of C1 esterase inhibitor in response to therapy
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Patient Preparations: Fasting 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:
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.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Frozen (preferred) | 28 days |
| Refrigerated | 28 days | |
| Ambient | 72 hours |
Reference Values
19-37 mg/dL
Day(s) Performed
Monday through Friday
Test Classification
This test has been cleared, approved, or is exempt by the US 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 |
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 (C1INF / C1 Esterase Inhibitor, Functional, 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; C1INF / C1 Esterase Inhibitor, Functional, 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.
Method Description
In this Siemens Nephelometer II method, the light scattered onto the antigen-antibody complexes is measured. The intensity of the measured scattered light is proportional to the amount of antigen-antibody complexes in the sample under certain conditions. If the antibody volume is kept constant, the signal behaves proportionally to the antigen volume.
A reference curve is generated by a standard with a known antigen content on which the scattered light signals of the samples can be evaluated and calculated as an antigen concentration. Antigen-antibody complexes are formed when a sample containing antigen and the corresponding antiserum are put into a cuvette. A light beam is generated with a light-emitting diode, which is transmitted through the cuvette. The light is scattered onto the immuno-complexes that are present. Antigen and antibody are mixed in the initial measurement, but no complex is formed yet. An antigen-antibody complex is formed in the final measurement.
The result is calculated by subtracting value of the final measurement from the initial measurement. The distribution of intensity of the scattered light depends on the ratio of the particle size of the antigen-antibody complexes to the radiated wavelength.(Instruction manual: Siemens Nephelometer II Operations. Siemens, Inc; Version 2.4, 07/2019)
Report Available
2 to 5 daysReject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Method Name
Nephelometry