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Test Code LAB2778 21-Hydroxylase Antibodies, Serum

Additional Codes

21OH


Ordering Guidance


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



Shipping Instructions


Ship specimen frozen on dry ice



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 a plastic vial to remove from cells or gel prior to shipping.


Secondary ID

607788

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)

Specimen Type

Serum

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

Negative

Interpretation

This is a qualitative test. A positive result indicates the presence of autoantibodies to 21-hydroxylase and is consistent with Addison disease.

 

Utilizing an index value of <45 as a negative cutoff, this assay has a clinical sensitivity and specificity of 87.0% (95% CI: 79.4%-92.2%) and 99.3% (95% CI: 97.5%-99.8%), respectively.

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; 04/2024)

Day(s) Performed

Wednesday

Report Available

3 to 9 days

Specimen Retention Time

2 weeks

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

83516

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