Test Catalog

Test ID: OH21    
21-Hydroxylase Antibodies, Serum

Useful For Suggests clinical disorders or settings where the test may be helpful

Investigation of adrenal insufficiency


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

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Chronic primary adrenal insufficiency (Addison disease) is most commonly caused by the insidious autoimmune destruction of the adrenal cortex and is characterized by the presence of adrenal cortex autoantibodies in the serum. It can occur sporadically or in combination with other autoimmune endocrine diseases, that together comprise Type I or Type II autoimmune polyglandular syndrome (APS).


The microsomal autoantigen 21-hydroxylase (55 kilodalton) has been shown to be the primary autoantigen associated with autoimmune Addison disease. 21-Hydroxylase antibodies are markers of autoimmune Addison disease, whether it presents alone, or as part of Type I or Type II (APS).

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

<1 U/mL

Reference values apply to all ages.

Interpretation Provides information to assist in interpretation of the test results

Positive results (> or =1 U/mL) indicate the presence of adrenal autoantibodies consistent with Addison disease.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Lipemic or grossly hemolyzed serum should not be used in this assay. Interpretation of test results requires consideration of other factors such as the clinical status of the patient, other test results, etc.

Supportive Data

Reagent Manufacturer's Data


Patient Group

Positive Rate

Healthy blood donors


Isolated Addison's disease


Addison's disease due to tuberculosis


APS type I


APS type II


Insulin dependent diabetes mellitus


Noninsulin dependent diabetes mellitus


Grave's disease


Hashimoto's disease


Myasthenia gravis



Mayo Data


Patient Group

Positive Rate

Normals from Mayo NV Study


+ Insulin Antibody


+ Thyroid stimulating Immunoglobin


+ Antinuclear Antibodies


+ Rheumatoid Factor


Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Husebye ES, Allolio B, Arlt W, et al: Consensus statement on the diagnosis, treatment and follow-up of patients with primary adrenal insufficiency. J Intern Med 2014 Feb;275(2):104-115

2. Tanaka H, Perez M, Powell M, et al: Steroid 21 hydroxylase autoantibodies: measurements with a new immunoprecipitation assay. J Clin Endocrinol Metab 1997;82:1440-1446