21-hydroxylase deficiency (patient information)

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21-hydroxylase Deficiency


What are the symptoms?

What are the causes?

Who is at highest risk?


When to seek urgent medical care?

Treatment options

Where to find medical care for 21-hydroxylase Deficiency?


What to expect (Outlook/Prognosis)?

Possible complications

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Mehrian Jafarizade, M.D [2]


21-hydroxylase deficiency is the most common type of congenital adrenal hyperplasia. Almost 95% of congenital adrenal hyperplasia patients is 21-hydroxylase deficient. Gene mutations are the cause of these diseases. Mutations in the CYP21A2 gene cause this disorder. CYP21A2 gene provides instructions for making an enzyme called steroid 21-hydroxylase, which enables the adrenal glands to convert cholesterol into other steroid hormones. Patients with 21-hydroxylase deficiency, the adrenal glands typically don't produce enough cortisol. Deficiency of 21-hydroxylase can interfere with normal growth and development in children and adults. Usual signs and symptoms include girls' external appearance change, boys may have 3-4 years early virilizing characteristics than the normal, even adrenal crisis in the newborn. Serum and urinary hormone level can help the diagnosis. Steroid therapy and surgery to correct the appearance and function of the genitals are the main treatments. Many patients with 21-hydroxylase deficiency can lead normal lives with appropriate treatment. Infants with untreated adrenal crisis may die within several weeks after birth.

What are the symptoms of 21-hydroxylase deficiency?

Signs and symptoms in infants:

In 21-hydroxylase, newborns develop severe symptoms shortly after birth due to loss of salt.

Signs and symptoms of adrenal hyperplasia in children and adults:

Girls will usually have normal internal female reproductive organs as normal girls. But some of their external appearance may change. Boys won't have any obvious problems at birth. However, they may have 3-4 years early virilizing characteristics than normal boys.

  • Irregular or absent menstruation in girls
  • Ambiguous genitalia or virilizing characteristics in girls, often appearing more male than female: Deep voice, early appearance of pubic and armpit hair, excessive hair growth and facial hair
  • Early appearance of masculine characteristics in boys: Deep voice, early appearance of pubic and armpit hair, enlarged penis, small testes, well-developed muscles
  • Rapid growth during childhood, but shorter than average final height
  • Infertility
  • Low bone density

What causes 21-hydroxylase deficiency?

Mutations in the CYP21A2 gene cause 21-hydroxylase deficiency.

Who is at risk for 21-hydroxylase deficiency?

Family history of 21-hydroxylase deficiency is the risk factor for this disease.


  • Blood or urine levels of hormones or their metabolites: In patients with 21-hydroxylase deficiency, doctors may see abnormal serum electrolytes and urine electrolytes, high levels of 17-hydroxyprogesterone, high levels of serum DHEA sulfate, high levels of urinary 17-ketosteroids, low levels of aldosterone and cortisol, normal or low urinary 17-hydroxycorticosteroids.
  • X-ray for bone age: This can be done in the department of radiation. It shows older bones than normal for the person's age.
  • Gene detection: This may be the most accurate test for the diagnosis. In patients with 21-hydroxylase deficiency, mutations of CYP21A2 gene can be detected.

When to seek urgent medical care?

  • Contact your doctor if your child has signs and symptoms that seem to suggest 21-hydroxylase deficiency.
  • For the women who may carry the mutate gene, you need to talk with your doctor, obtain appropriate information about the condition and the risk of having an affected child, and to decide on whether to have children.

Treatment options

The goal of treatment is to return hormone levels to normal. The treatments include steroid therapy and surgery. Talk to you or your kid's doctor about side effects and your family's preferences.

  • Determination the gender of a baby: When the baby with ambiguous genitalia born, the health care provider will determine the gender by checking the chromosomes.
  • Steroid therapy: Dexamethasone, fludrocortisone, or hydrocortisone every day. During times of stress, such as severe illness or surgery, they may need additional doses of medicine.
  • Surgery: For female infants with virilizing characteristics, doctors recommend reconstructive surgery to correct the appearance and function of the genitals between 2 and 6 months of age.

Diseases with similar symptoms

Where to find medical care for 21-hydroxylase deficiency?

Directions to Hospitals Treating 21-hydroxylase deficiency


Doctors often recommend genetic counseling for parents who have 21-hydroxylase deficiency. Early diagnosis during pregnany can minimize or even eliminate symptoms after birth.

What to expect (Outook/Prognosis)?

Prognosis of 21-hydroxylase deficiency are usually good. But when adrenal crisis happens and is untreated, the patient may die within 1-6 weeks after birth.


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