C1 Esterase Inhibitor, Functional

FC1EQ, C1 Esterase Inh, Func (QN), Functional C1 Esterase, C-1-Esterase Inhibitor Functional Assay, Quantitative, 

C1 Esterase Inhibitor Functional, Serum

Test Codes

EPIC: LAB1230884, Beaker: XC1IF, Quest: 297

Department

Send Outs

Instructions

It is preferred that the patient fasts for 12 hours prior to specimen collection, but not required.

Specimen Collection Criteria

Collect (preferred specimen): One plain Red-top tube.

Unacceptable: Gold-top Serum Separator Tube (SST).

Physician Office/Draw Specimen Preparation

Critical frozen. Let specimen clot 30 minutes, then centrifuge to separate serum from cells within one hour of collection. Transfer serum to plastic transport tube and freeze (-20°C/-4°F or below) prior to transport.

Preparation for Courier Transport

Transport: 1.0 mL serum, frozen (-20°C/-4°F or below). (Minimum: 0.2 mL)

Rejection Criteria

Specimens not collected and processed as indicated.

In-Lab Processing

Critical frozen. Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to a plastic transport tube and freeze (-20°C/-4°F or below) immediately.

Transport: 1.0 mL serum, frozen (-20°C/-4°F or below). (Minimum: 0.4 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): 30 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL.

Performed

Sunday, Tuesday, Thursday.
Results available in 2-4 days.

Reference Range

≥68 %          Normal
41-67 %      Equivocal
≤40 %         Abnormal

Test Methodology

Enzyme Immunoassay Assay (EIA).

CPT Codes

86161
LOINC:  4477-6

Contacts

Last Updated

12/17/2025