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Complement C1 Esterase Inhibitor

CPT: 86160
Updated on 09/22/2020
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  • C1 Esterase Inhibitor, Antigen
  • C1 Inactivator
  • C1 Inhibitor
  • Esterase Inhibitor
  • HANE Assay
  • Hereditary Angioneurotic Edema Test

Test Includes

Total immunoreactive level (immunologic/quantitative)

Expected Turnaround Time

2 - 4 days

Related Documents

Specimen Requirements




1 mL

Minimum Volume

0.5 mL (Note: This volume does not allow for repeat testing.)


Red-top tube or gel-barrier tube


Separate serum from cells within 30 to 60 minutes after collection. Transfer specimen to a plastic transport tube.

Storage Instructions

Maintain specimen at room temperature.

Stability Requirements



Room temperature

14 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Microbially-contaminated samples; hemolysis; gross lipemia that cannot be cleared by ultracentrifugation; citrated plasma (heparinized plasma is acceptable)

Test Details


C1 esterase inhibitor is decreased in hereditary angioneurotic edema; decrease may be functional or quantitative


Immunologic, quantitative

Reference Interval

21−39 mg/dL

Additional Information

The more common form (85% of patients) of hereditary angioneurotic edema is due to an absolute decrease in the amount of C1 esterase inhibitor. A less common form (15% of patients) is due to a functional defect where quantitative levels may be normal. Both abnormalities must be tested for due to the potential life-threatening nature of the illness.

In addition to decreased C1 esterase inhibitor in the serum of patients with hereditary angioneurotic edema, a unique polypeptide kinin is increased in plasma from C1 esterase inhibitor deficient patient during attacks of swelling. Danazol, a synthetic androgenic inhibitor of gonadotropin release, with little virilizing potential, decreases the number of clinical attacks in cases of hereditary angioneurotic edema. Patients with attacks of hereditary angioneurotic edema also have low total complement, C4 and C2. Consequently, measurement of serum C4 is an often used test. Hereditary angioneurotic edema is transmitted as an autosomal dominant trait. Heterozygotes also show decreased levels of C1 esterase inhibitor. During acute attacks of the disease, complement factors C4 and C2 can be markedly reduced, but C1 and C3 are normal. The initiating stimulus of clinical attacks is often unknown.

Angioedema may also be an acquired illness. The acquired form includes nonhereditary C1 esterase deficiency; drug induced, allergic, and idiopathic forms, angioedema associated with autoimmune disease, especially with systemic lupus erythematosus and hypereosinophilia; angioedema occasionally associated with malignancy; and angioedema caused by physical stimuli. Angioedema has occasionally been known to precede development of lymphoproliferative disorders.


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
004648 C1 Esterase Inhibitor, Serum 4477-6 004648 C1 Esterase Inhibitor, Serum mg/dL 4477-6

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