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Test Code OH21 21-Hydroxylase Antibodies, Serum

Performing Laboratory

Mayo Medical Laboratories in Rochester

Reporting Name

21-Hydroxylase Ab, S

Specimen Type

Serum


Specimen Required


Collection Container/Tube: 

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL


Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross reject

Icterus

Mild OK; Gross OK

Other

NA

Specimen Stability Information

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

Specimen Minimum Volume

0.19 mL

Day(s) and Time(s) Performed

Thursday; 2 p.m.

Specimen Retention Time

2 weeks

Analytic Time

2 days

Reference Values

<1 U/mL

Reference values apply to all ages.

Useful For

Investigation of adrenal insufficiency

 

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

Method Name

Immunoabsorption Assay

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

83519

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

Clinical Information

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).

Interpretation

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

Cautions

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.

Clinical Reference

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

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)

Supportive Data

Reagent Manufacturer's Data

 

Patient Group

Positive Rate

Healthy blood donors

6/243

Isolated Addison's disease

43/60

Addison's disease due to tuberculosis

0/9

APS type I

11/12

APS type II

27/27

Insulin dependent diabetes mellitus

4/150

Noninsulin dependent diabetes mellitus

0/32

Grave's disease

1/77

Hashimoto's disease

1/67

Myasthenia gravis

0/35

 

Mayo Data

 

Patient Group

Positive Rate

Normals from Mayo NV Study

1/50

+ Insulin Antibody

0/5

+ Thyroid stimulating Immunoglobin

0/5

+ Antinuclear Antibodies

0/10

+ Rheumatoid Factor

0/10