Skip Ribbon Commands
Skip to main content
Sign In
Navigate Up

26499 C1 Esterase Inhibitor, Functional, Serum (C1INF)

C1 Esterase Inhibitor, Functional, Serum (C1INF)
Test Code: C1INFSO
Synonyms/Keywords

C1 Esterase Inh,Func (QN)

Functional C'1 Esterase

Hereditary Angioedema Panel (3 tests)

Hereditary Angioedema, HAE

Useful For

Diagnosing hereditary angioedema

Monitoring response to C1 esterase inhibitor replacement therapy

Specimen Requirements
Fasting RequiredSpecimen TypePreferred Container/TubeAcceptable Container/TubeSpecimen VolumeSpecimen Minimum Volume
(allows for 1 repeat)		Pediatric Minimum Volume
(no repeat)
​Preferred, but not required​Serum​Red Top Tube (RTT)​Serum Separator Tube (SST)1 mL​0.4 mL​
Collection Processing Instructions

Collection Instructions:

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

2. Centrifuge at 4 degrees C and aliquot serum into a 5-mL plastic vial.

3. Freeze specimen within 30 minutes.

Specimen Stability Information
Specimen TypeTemperatureTime
​Serum​Frozen (preferred)​28 days
Rejection Criteria
DRY ICE REGULAR HOURS: Centrifuge at 4 degrees C, aliquot, transport on dry ice
OFF HOURS: Centrifuge at 4 degrees C, aliquot, freeze within 30 minutes. Transport next working day on dry ice.
Interference

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

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

Performing Laboratory Information
Performing LocationDay(s) Test PerformedReport AvailableMethodology/Instrumentation
​Mayo Clinic Laboratories​Varies​3 to 5 days​Enzyme Immunoassay (EIA)
Reference Lab
Mayo Clinic Laboratories
Reference Range Information
Performing LocationReference Range
​Mayo Clinic Laboratories​

>67% normal (normal)

41-67% normal (equivocal)

<41% normal (abnormal)

Interpretation

The C1 esterase inhibitor (C1-INH) concentration assay can be used to distinguish type I hereditary angioedema (HAE), with low C1-INH concentration, from type II HAE characterized by normal or elevated concentration. Furthermore, serum C1q concentrations can be used to differentiate HAE from acquired angioedema (AAE) forms of angioedema as the latter is characterized by decreased C1q antigen concentration and autoantibodies against C1-INH. Genetic analysis for SERPING1 variants status may also help exclude HAE.

-Nonfunctional C1-INH results are consistent with HAE

-Patients with current attacks may also have low C2 and C4 concentrations due to C1 activation and complement activation of the classical pathway (consumption).

-Patients with acquired C1-INH deficiency have a low C1q concentration and/or function in addition to low C1-INH. 

Outreach CPTs
CPTModifier
(if needed)		QuantityDescriptionComments
​83520​​1​​
Synonyms/Keywords

C1 Esterase Inh,Func (QN)

Functional C'1 Esterase

Hereditary Angioedema Panel (3 tests)

Hereditary Angioedema, HAE

Ordering Applications
Ordering ApplicationDescription
​COM​C1 Esterase Inhib, Funct Assay
​Cerner​C1 Esterase Inhib Funct (C1INF)
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting RequiredSpecimen TypePreferred Container/TubeAcceptable Container/TubeSpecimen VolumeSpecimen Minimum Volume
(allows for 1 repeat)		Pediatric Minimum Volume
(no repeat)
​Preferred, but not required​Serum​Red Top Tube (RTT)​Serum Separator Tube (SST)1 mL​0.4 mL​
Collection Processing

Collection Instructions:

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

2. Centrifuge at 4 degrees C and aliquot serum into a 5-mL plastic vial.

3. Freeze specimen within 30 minutes.

Specimen Stability Information
Specimen TypeTemperatureTime
​Serum​Frozen (preferred)​28 days
Rejection Criteria
DRY ICE REGULAR HOURS: Centrifuge at 4 degrees C, aliquot, transport on dry ice
OFF HOURS: Centrifuge at 4 degrees C, aliquot, freeze within 30 minutes. Transport next working day on dry ice.
Interference

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

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

Useful For

Diagnosing hereditary angioedema

Monitoring response to C1 esterase inhibitor replacement therapy

Reference Range Information
Performing LocationReference Range
​Mayo Clinic Laboratories​

>67% normal (normal)

41-67% normal (equivocal)

<41% normal (abnormal)

Interpretation

The C1 esterase inhibitor (C1-INH) concentration assay can be used to distinguish type I hereditary angioedema (HAE), with low C1-INH concentration, from type II HAE characterized by normal or elevated concentration. Furthermore, serum C1q concentrations can be used to differentiate HAE from acquired angioedema (AAE) forms of angioedema as the latter is characterized by decreased C1q antigen concentration and autoantibodies against C1-INH. Genetic analysis for SERPING1 variants status may also help exclude HAE.

-Nonfunctional C1-INH results are consistent with HAE

-Patients with current attacks may also have low C2 and C4 concentrations due to C1 activation and complement activation of the classical pathway (consumption).

-Patients with acquired C1-INH deficiency have a low C1q concentration and/or function in addition to low C1-INH. 

For more information visit:
Performing Laboratory Information
Performing LocationDay(s) Test PerformedReport AvailableMethodology/Instrumentation
​Mayo Clinic Laboratories​Varies​3 to 5 days​Enzyme Immunoassay (EIA)
Reference Lab
Mayo Clinic Laboratories
For billing questions, see Contacts
Outreach CPTs
CPTModifier
(if needed)		QuantityDescriptionComments
​83520​​1​​
For most current information refer to the Marshfield Laboratory online reference manual.