Test ID: OH21
21-Hydroxylase Antibodies, Serum
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
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
Method Name A short description of the method used to perform the test
Immunoabsorption Assay
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
21-OH Ab
Adrenal Antibody
Hydroxylase Antibody
Anti-Adrenal Antibody
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | Mild OK; Gross OK |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Frozen (preferred) | 14 days |
| Refrigerated | 7 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Chronic primary adrenal insufficiency (Addison's 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's disease. 21-Hydroxylase antibodies are markers of autoimmune Addison's 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's 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. The assay reagents are labeled "For Research Use Only"; therefore 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 | 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 |
| Non-insulin 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 |
| + Anti-nuclear Antibodies | 0/10 |
| + Rheumatoid Factor | 0/10 |
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
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 Describes how the test is performed and provides a method-specific reference
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)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Thursday; 2 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
83519
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 81970 | 21-Hydroxylase Ab, S | 17781-6 |
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