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Test Code ADRENAL AB 21-Hydroxylase Antibodies, Serum

Reporting Name

21-Hydroxylase Ab, S

Useful For

Investigation of adrenal insufficiency


Aid in the detection of those at risk of developing autoimmune adrenal failure in the future

Specimen Required

Collection Container/Tube: 

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Seattle Children's Hospital Note:

Collect 2 mL whole blood in a Red top.

Specimen Type


Specimen Minimum Volume

0.19 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Frozen (preferred) 14 days
  Refrigerated  7 days

Day(s) and Time(s) Performed

Thursday; 2 p.m.

Seattle Children's Hospital Note:

TAT: 4 - 11 days

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Immunoabsorption Assay

Method Description

Calibrators, controls, and patient specimens are incubated overnight with I(125) 21-hydroxylase. Antibody, if present, binds to the 21-hydroxylase during this time. Protein A is added to precipitate the antibodies present, the assay tubes are centrifuged, and the pellet is counted. The amount of radioactivity in the pellet is directly proportional to the amount of antibody contained in the specimen.(Package insert: 21-Hydroxylase [21-OH] Antibody Kit. Kronus, San Clemente, CA)

Reference Values

<1 U/mL

Reference values apply to all ages.

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


LOINC Code Information

Test ID Test Order Name Order LOINC Value
OH21 21-Hydroxylase Ab, S In Process


Result ID Test Result Name Result LOINC Value
81970 21-Hydroxylase Ab, S 17781-6

Reject Due To


Mild OK; Gross reject


Mild OK; Gross reject


Mild OK; Gross OK