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C1 Esterase Inhibitor, Functional
Message*Take to processing to be spun down. Specimen must be spun down and frozen within an hour from collection.
Test Code
297
Alias/See Also
LAB769
CPT Codes
86161
Preferred Specimen
1 mL frozen serum collected in a red-top tube (no gel)
Minimum Volume
0.2 mL
Instructions
Freeze serum within 1 hour of time drawn.
Do not use gel barrier tubes. Do not submit the sample in a glass tube. Do not thaw.
Do not use gel barrier tubes. Do not submit the sample in a glass tube. Do not thaw.
Transport Container
Transport tube
Transport Temperature
Frozen
Specimen Stability
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 30 days
Refrigerated: Unacceptable
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Grossly lipemic • Serum separator tube (SST) • Received thawed
Methodology
Enzyme Immunoassay (EIA)
Setup Schedule
Mon-sat
Reference Range
| ≥68 % | Normal |
| 41-67 % | Equivocal |
| ≤40 % | Abnormal |
Less than 40% of the reference functional activity indicates a likely diagnosis of hereditary angioedema or acquired C1 Inhibitor deficiency.
Clinical Significance
C1 esterase is decreased in angioedema. The inherited form is usually diagnosed in the first two decades of life. The acquired form affects primarily adults with autoimmune or lymphoproliferative disorders. Approximately 15% of patients with hereditary angioedema have a normal concentration of the protein but it is dysfunctional.
Performing Laboratory
| Quest Diagnostics Nichols Institute-Chantilly VA |
| 14225 Newbrook Drive |
| Chantilly, VA 20151-2228 |