Home
HelpEpic Test Code LAB850 C1 Esterase Inhibitor Antigen, Serum
Additional Codes
MML Code: C1ES
NY State Approved
YesPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Reporting Name
C1 Esterase Inhibitor Antigen, SMethod Name
Nephelometry
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen (preferred) | 28 days | |
| Refrigerated | 28 days | ||
| Ambient | 72 hours |
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.
Blood Tube Draw Volume
Min 50% draw volume
50% of the tube fill volume is required for proper blood to additive ratio.
Specimen Type
SerumSpecimen Minimum Volume
0.5 mL
Reference Values
19-37 mg/dL
Report Available
2 to 5 daysDay(s) Performed
Monday through Friday
CPT Code Information
83883
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | Reject |
| Gross icterus | OK |
Useful 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.