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Test Code 0255232 C1 Esterase Inhibitor, Functional Assay, Serum

Additional Codes

Mayo Test ID
FC1EQ

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Diagnosing hereditary angioedema and for monitoring response to therapy

Method Name

Enzyme Immunoassay (EIA)

Reporting Name

C1 Esterase Inhib, Functional

Specimen Type

Serum Red


Specimen Required


Patient Preparation: Patient should be fasting.

Collection Container/Tube: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

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

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

3. Freeze specimen within 30 minutes.


CentraCare Laboratory Services Note:

Freeze serum within 1 hour of collection and submit frozen.

Specimen Minimum Volume

0.1 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Red Frozen 28 days

Reject Due To

Hemolysis

Mild OK; Gross OK

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross reject

Other

Serum gel tube, heat-inactivated samples

Reference Values

>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.

Day(s) and Time(s) Performed

Varies

Analytic Time

1 day

Specimen Retention Time

14 days

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

83520

LOINC Code Information

Test ID Test Order Name Order LOINC Value
FC1EQ C1 Esterase Inhib, Functional 48494-9

 

Result ID Test Result Name Result LOINC Value
81493 C1 Esterase Inhib, Functional, QN 48494-9