Skip Ribbon Commands
Skip to main content
Sign In

22385 C1 Esterase Inhibitor, Functional (FC1EQ)

C1 Esterase Inhibitor, Functional (FC1EQ)
Test Code: C1ESO
Synonyms/Keywords
C1 Esterase Inh,Func (QN), Functional C'1 Esterase, Hereditary Angioedema Panel (3 tests), Hereditary Angioedema, HAE
Useful For
Diagnosing hereditary angioedema and for monitoring response to therapy
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​Yes Serum​ ​Red Top Tube (RTT) ​1 mL ​0.1 mL
Collection Processing Instructions

1. Immediately after specimen collection, place the tube on wet ice.

2. Centrifuge at 4 degrees C and separate serum from clot.

3. Freeze specimen within 30 minutes.

Specimen Stability Information
Specimen Type Temperature Time
​Serum Frozen​ ​28 days
Rejection Criteria
Serum Separator Tube​ ​
​Gross Icterus
​Heat-inactivated samples
Interference

​This assay is a functional test and is dependent on correct sampling, storage, and shipping conditions.

Absent (or low) C1 inhibitor (C1-INH) function should be confirmed with a new serum specimen to confirm that inactivation has not occurred during shipping.

Performing Laboratory Information
Performing Location Day(s) Test Performed Report Available Methodology/Instrumentation
Mayo Clinic Laboratories​​ Varies​ 1 to 5 days​
Enzyme Immunoassay (EIA)
Reference Lab
Reference Range Information
Performing Location Reference Range
Mayo Clinic Laboratories​​
>67% normal (normal)
41-67% normal (equivocal)
<41% normal (abnormal)
Interpretation

Hereditary angioedema (HAE) can be definitely diagnosed by laboratory tests demonstrating a marked reduction in C1 inhibitor (C1-INH) antigen or abnormally low functional C1-INH levels in a patient's plasma or serum that has normal or elevated antigen.

Nonfunctional results are consistent with HAE.

Patients with current attacks will also have low C2 and C4 levels due to C1 activation and complement consumption.

Patients with acquired C1-INH deficiency have a low C1q in addition to low C1-INH. 

Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​83520
Synonyms/Keywords
C1 Esterase Inh,Func (QN), Functional C'1 Esterase, Hereditary Angioedema Panel (3 tests), Hereditary Angioedema, HAE
Ordering Applications
Ordering Application Description
​Centricity ​C1 Est Inhib, Funct
​Cerner C1 Esterase Inhibitor, Functional (81493)​
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​Yes Serum​ ​Red Top Tube (RTT) ​1 mL ​0.1 mL
Collection Processing

1. Immediately after specimen collection, place the tube on wet ice.

2. Centrifuge at 4 degrees C and separate serum from clot.

3. Freeze specimen within 30 minutes.

Specimen Stability Information
Specimen Type Temperature Time
​Serum Frozen​ ​28 days
Rejection Criteria
Serum Separator Tube​ ​
​Gross Icterus
​Heat-inactivated samples
Interference

​This assay is a functional test and is dependent on correct sampling, storage, and shipping conditions.

Absent (or low) C1 inhibitor (C1-INH) function should be confirmed with a new serum specimen to confirm that inactivation has not occurred during shipping.

Useful For
Diagnosing hereditary angioedema and for monitoring response to therapy
Reference Range Information
Performing Location Reference Range
Mayo Clinic Laboratories​​
>67% normal (normal)
41-67% normal (equivocal)
<41% normal (abnormal)
Interpretation

Hereditary angioedema (HAE) can be definitely diagnosed by laboratory tests demonstrating a marked reduction in C1 inhibitor (C1-INH) antigen or abnormally low functional C1-INH levels in a patient's plasma or serum that has normal or elevated antigen.

Nonfunctional results are consistent with HAE.

Patients with current attacks will also have low C2 and C4 levels due to C1 activation and complement consumption.

Patients with acquired C1-INH deficiency have a low C1q in addition to low C1-INH. 

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Report Available Methodology/Instrumentation
Mayo Clinic Laboratories​​ Varies​ 1 to 5 days​
Enzyme Immunoassay (EIA)
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​83520
For most current information refer to the Marshfield Laboratory online reference manual.