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C1 Esterase Inhibitor Deficiency Panel

Item Value
Available Stat? No
Test code C1EI
Performed by Quest
Sendout? Yes
Patient Preparation An 8 hour fast before specimen collection is preferred
Collection Instructions Collect and allow to clot in ice slurry. Bring immediately to lab on ice.

Note special sample requirements for B&T patients
Container type Red top on ice (Gold top NOT acceptable)
Lavender top on ice for B&T patients
Amount to Collect 6 mL blood
Sample type Serum
EDTA Plasma for B&T patients
Preferred volume 3 mL serum in 3 aliquots of 1 mL each
Min. Volume 0.5 mL serum each
UCSF Rejection Criteria Not delivered on ice. Sample collected in Gold top
Processing notes Centrifuge immediately under refrigeration. Freeze three separate aliquots at ≤ 60C in plastic tubes and ship on dry ice. Order Quest # 44768P, 298 and 44784P

Note that LabCorp requires EDTA plasma for B&T patients.
Units see normal ranges
Normal range C1EI activity (by decay of C1r):
Normal > 67%
Equivocal 41-67%
Abnormal < 41%

C1EI quantitation 11-26 mg/dL
C1q quantitation 5.0-8.6 mg/dL
Synonyms Angioedema Panel; C1-esterase inhibitor; angioneurotic edema; anti-C1r; C1r; C4DX/C4 ratio; HAE; HAN E; Hereditary angioneurotic edema
Turn around times Test performed Tuesday and Thursday. Turnaround time: 3-8 days.
Additional information Includes C1EI activity, C1EI quantitation and C1q quantitation.

The results expected of these assays in the different clinical settings in which low C4 levels are seen are:

Basis of
activity by
C1r decay
Hereditary angioedema
Abnormal Decreased Normal
Hereditary angioedema
?Abnormal Normal Normal
Acquired ?Abnormal Decreased Decreased
Normal Normal Normal

CPT coding 86161-90
LOINC code 4477-6
Last Updated 6/21/2016 08:08:12
Entry Number 149
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