C1 Esterase Inhibitor, Functional, Serum
Use
Diagnosing hereditary angioedema and monitoring response to C1 esterase inhibitor replacement therapy. C1 esterase inhibitor (C1-INH) plays a crucial role in regulating enzymes of the complement, coagulation, fibrinolytic, and kinin-forming systems. Deficiencies in functionally active C1-INH can lead to life-threatening angioedema. Evaluation is essential for differentiating between hereditary and acquired forms of angioedema, guiding treatment, and confirming diagnoses. Understanding the variation in C1-INH activity and related protein levels aids in determining the type and appropriate management of angioedema.
Special Instructions
Fasting for 8 hours before specimen collection is preferred but not required. Use the Sarstedt Aliquot Tube, 5 mL (T914) for collection. Immediately place the tube on wet ice post-collection, then centrifuge at 4°C and aliquot serum into a plastic vial before freezing. If a refrigerated centrifuge is unavailable, a room temperature centrifuge can be used, provided the specimen is kept on ice before and immediately after centrifugation, with serum aliquoted and frozen promptly.
Limitations
This assay is a functional test reliant on proper sample collection, storage, and transport. Low or absent C1 esterase inhibitor function should be confirmed with a fresh serum specimen to ensure no inactivation occurred during transport. False positives are common due to low disease prevalence; repeated testing is recommended for confirmation.
New York Approved
Methodology
Immunoassay (ELISA)
Biomarkers
LOINC Codes
- 48494-9
- 48494-9
Result Turnaround Time
3-5 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.4 mL
Container
Red top (preferred), Serum gel (acceptable); Aliquot into plastic vial for submission
Collection Instructions
Place tube on wet ice immediately after collection, centrifuge at 4°C, aliquot serum into a plastic vial, and freeze within 30 minutes. Samples must be placed on dry ice if not frozen immediately.
Patient Preparation
Fasting for 8 hours is preferred but not required.
Causes for Rejection
Gross icterus; Heat-inactivated samples
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 28 days |