Laboratory Test Information Guide

Details for C1 Esterase Inhibitor, Function

Test Name: C1 Esterase Inhibitor, Function
Alternate Name(s): C1INF
C1 Inhibitor function
C1 Esterase Inhibitor functional assay
Laboratory: Core
Specimen Type: 4.5 mL (3.2% Sodium Citrate) Light Blue top Vacutainer tube
Collection Information: The only acceptable sample is Sodium Citrate Plasma.
1 mL plasma is required for testing.
Separate platelet-poor plasma immediately. Freeze as soon as possible.
Specify "Functional" on requisition.
Test Schedule: Referred out Monday-Thursday
Turnaround time from when specimen
is received in testing laboratory:
15 days
Reference Range: 0.75 - 1.59 U/mL
Effective Date: 2010-03-18
Revised Date: 2020-06-22
Critical Value:  
Interpretive Comments: This test evaluates the functional activity of C1 inhibitor protein utilizing a chromogenic based method.

For proper assessment of angioedema please correlate with other clinical features and with the results of quantitative levels of both C1 inhibitor protein and C4.

This assay is sensitive to sample handling and storage conditions. A repeat test with a fresh sample is recommended for results with borderline low/abnormal functional activity (0.69 - 0.74 U/mL).
Special Processing: Centrifuge at 4 C and separate platelet-poor plasma immediately. Freeze as soon as possible.
Comments: This test is available exclusively to LHSC/SJH physicians.

For more information, please contact:

Senior Technologist
Immunology Lab
519-685-8500 ext. 35541

Method of Analysis: Chromogenic
Critical Information Required:  
Storage & Shipment: Store and send frozen. If the specimen thaws, it is unsuitable for analysis.
System Codes: 
Referred To: In-Common Laboratories

Questions? Comments? Contact Laura Gopaul