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Anti-21-Hydroxylase Antibody

Published: July 27, 2026Updated: August 25, 2026

The anti-21-hydroxylase antibody test measures the presence of antibodies against the 21-hydroxylase enzyme, which is crucial for cortisol synthesis.

Quick summary

This test detects antibodies against 21-hydroxylase, aiding in the diagnosis of autoimmune adrenal disorders.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
U/mL
Clinical utility
diagnostic
Result kind
qualitative
FDA-cleared
Roche 21-OH Ab, Iowa 21-Hydroxylase Ab
interpretation: {"text":"0–1 U/mL: No significant antibodies detected.","label":"Normal"}; {"text":">1 U/mL: Possible autoimmune adrenal disorder.","label":"Elevated"}

The anti-21-hydroxylase antibody test is primarily used to diagnose autoimmune conditions affecting the adrenal glands, such as Addison's disease. In these conditions, the body produces antibodies that attack the 21-hydroxylase enzyme, leading to decreased cortisol production.

Cortisol is a vital hormone that helps the body respond to stress, regulate blood sugar, and reduce inflammation. A deficiency in cortisol can cause a range of symptoms, including fatigue, weight loss, and low blood pressure.

The normal reference range for anti-21-hydroxylase antibodies is 0–1 U/mL. Levels above this range may indicate the presence of an autoimmune adrenal disorder.

Frequently asked questions

What does a positive anti-21-hydroxylase antibody test mean?
A positive test indicates the presence of antibodies against 21-hydroxylase, suggesting an autoimmune adrenal disorder like Addison's disease.
Can this test be used to monitor disease progression?
Yes, it can help monitor the progression of autoimmune adrenal disorders and the effectiveness of treatment.
  1. 1
    Addison's Disease - DiagnosisSource
  2. 2
    21-Hydroxylase AutoantibodiesSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy