Days Set Up
Varies; test performed twice per week
Analytic Time

2 - 6 days

MiChart Code
C1 Esterase Inhibitor, Functional
Soft Order Code

Test Updated:


Hereditary Angioedema (HAE)
HAE (Hereditary Angioedema)
Complement C1 Esterase Inhibitor, Functional
Functional C'1 Esterase
C1 Esterase Inhib, Functional

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All specimens should be accompanied by a requisition.

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Order Kits and Supplies

MLabs provides all the supplies necessary for the collection of specimens.

Test FAQ

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Test Overview

Test Methodology

Enzyme Immunoassay (EIA)

Test Usage

The diagnosis of C1 esterase inhibitor deficiency (hereditary angioedema) or monitoring response to therapy. If C1 Esterase Inhibitor Quantitation is low, it is not necessary to do the functional assay, as it will also be low.

Reference Range

Normal: >67%, Equivocal: 41 - 67%, Abnormal:

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Specimen Requirements


A fasting specimen is preferred but not required. Collect specimen in a red top tube; do not use SST tube. Immediately place on wet ice. Centrifuge, aliquot serum into a plastic vial and freeze immediately. Hemolytic or thawed specimens are unacceptable.

Yellow Top Tube
Red Top Tube
Normal Volume
1 mL serum
Minimum Volume
0.1 mL serum

Billing Information

CPT Code
Pro Fee Code

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Our High Standard

Quality that sets us apart

As the reference laboratory division of Michigan Medicine's Department of Pathology, MLabs shares the institution's commitment to applying established quality principles to clinical laboratory testing. Like other large organizations in complex, consequential fields, we rely on an established approach to monitor quality throughout the testing process.