C1 Esterase Inhibitor, Functional

Understand what C1 Esterase Inhibitor, Functional signals

LOINC codes: 10634-4
Commercial laboratory assays: 1

We have not added a physiological summary for this biomarker yet. Compare the commercial laboratory assays and population reference ranges below.

Compare commercial laboratory assays for C1 Esterase Inhibitor, Functional

Check orderable catalog codes, specimen types, fasting requirements, and demographic reference ranges across laboratories.

C1 Esterase Inhibitor, Functional

Laboratory: Quest Diagnostics
Test code: 297
Specimen: Serum
Fasting: Not stated
LOINC: 10634-4
Turnaround: Set up: Mon, Wed, Fri (a.m.); Report available: 4 days

Laboratory assay overview

C1 esterase is decreased in angioedema. The inherited form is usually diagnosed in the first two decades of life. The acquired form affects primarily adults with autoimmune or lymphoproliferative disorders. Approximately 15% of patients with hereditary angioedema have a normal concentration of the protein but it is dysfunctional.

Quest Diagnostics population reference ranges

Quest Diagnostics calculates these statistical intervals for this specific assay and demographic group, not as universal optimal targets.

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

View complete laboratory reference notes

≥68 % Normal 41-67 % Equivocal ≤40 % Abnormal Less than 40% of the reference functional activity indicates a likely diagnosis of hereditary angioedema or acquired C1 Inhibitor deficiency.

Quest Diagnostics test directory, test code 297

Verify these ranges and sources

We compile every detail above directly from named laboratory directories and published clinical studies. Laboratories calculate standard reference intervals from the statistical distribution of tested populations for a specific assay method and demographic group, rather than setting universal optimal targets.

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