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HelpTEST ID 21OH 21-Hydroxylase Antibodies, Serum
Reporting Name
21-Hydroxylase Ab, SSpecimen Type
SerumOrdering 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.
Specimen Minimum Volume
0.2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Frozen | 14 days |
Method Name
Enzyme-Linked Immunosorbent Assay (ELISA)
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Reference Values
Negative
Day(s) Performed
Wednesday
Report Available
3 to 9 daysSpecimen Retention Time
2 weeksPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
83516
Useful For
Investigating adrenal insufficiency
Aiding in the detection of those at risk of developing autoimmune adrenal failure in the future
Highlights
Addison disease is the most frequent cause of primary adrenal insufficiency.
Autoantibodies against 21-hydroxylase are present in up to 90% of Addison disease cases.
Measurement of anti-21-hydroxylase autoantibodies is useful in the evaluation of the cause of established primary adrenal insufficiency.
Clinical Information
Adrenal insufficiency is caused by failure of the adrenal cortex to produce cortisol. This failure can result from loss of function of the adrenal glands (ie, primary adrenal insufficiency). This is most frequently caused by autoimmune adrenalitis or Addison disease accounting for 68% to 94% of cases. It can occur sporadically or in combination with other autoimmune endocrine diseases that together comprise type I or II autoimmune polyglandular syndrome (APS).
Antibodies that react with several steroidogenic enzymes (most often 21-hydroxylase) are present in the serum of up to 86% of patients with autoimmune primary adrenal insufficiency but only rarely in patients with other causes of adrenal insufficiency. Therefore, 21-hydroxylase autoantibodies are markers of autoimmune Addison disease, whether present alone or as part of type I or II APS. The measurement of 21-hydroxylase autoantibodies is an important step in the investigation of adrenal insufficiency and may aid in the detection of those at risk of developing autoimmune adrenal failure in the future.
Cautions
Lipemic or grossly hemolyzed serum should not be used in this assay.
Results should be interpreted in the context of clinical symptoms and adrenal functional confirmatory tests.
In rare cases, some individuals can develop antibodies to mouse or other animal antibodies (often referred to as human anti-mouse antibodies [HAMA] or heterophile antibodies), which may cause interference in some immunoassays. Caution should be used in interpretation of results and the laboratory should be alerted if the result does not correlate with the clinical presentation.
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)