Sign in →

Test Code Adrenal Ab 21-Hydroxylase Antibodies, Serum

Ordering Guidance

Testing for auto-antibodies against 21-hydroxylase is recommended following confirmation of adrenal insufficiency to help differentiate between causes of primary adrenal insufficiency

Shipping Instructions

Ship serum specimen frozen

Specimen Required

Collection Container/Tube: 

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial to remove from cells or gel prior to shipping.

Useful For

Investigating adrenal insufficiency


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

Method Name

Enzyme-linked Immunosorbent Assay (ELISA)

Reporting Name

21-Hydroxylase Ab, S
Seattle Children's Hospital Note:

SCH Clinical System Name: 21-Hydroxylase Antibodies

Specimen Type


Specimen Minimum Volume

0.2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Frozen 14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Reference Values


Method Description

A reference preparation, controls, and patient specimens are incubated with a reaction enhancer overnight in a coated enzyme-linked immunosorbent assay (ELISA) plate. 21-Hydroxylase (21-OH) antibodies (Ab) act divalently and form a bridge between 21-OH Ab coated on ELISA plate wells and liquid phase 21-OH biotin. The resulting antigen-antibody-antigen complexes are then detected by the addition of streptavidin peroxidase and tetramethylbenzidine to produce a colorogenic reaction. Stop solution is added to halt the reaction, and absorbance is read using an ELISA plate reader. The absorbance of each well is directly proportional to the amount of antibody present. Positive and negative determinations are based on index values. Index values are calculated from the mean value of duplicate sample wells and compared to a reference value.(Package insert: 21-Hydroxylase Autoantibody (21-OHAb) ELISA Kit, Kronus; 01/2019)

Day(s) Performed


Report Available

3 to 9 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US 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
21OH 21-Hydroxylase Ab, S 85363-0


Result ID Test Result Name Result LOINC Value
607788 21-Hydroxylase Ab, S 85363-0