Aldosterone synthesis in salt-wasting congenital adrenal hyperplasia with complete absence of adrenal 21-hydroxylase

Article Abstract:

Patients with congenital adrenal hyperplasia have a defect in the activity of the enzyme 21-hydroxylase. This enzyme, normally found within the adrenal cortex, is a part of the steroid synthesis pathway which produces cortisol. Patients with impaired 21-hydroxylase activity have decreased levels of cortisol; in addition, more than two-thirds have deficient aldosterone production. The hyperplasia (overdevelopment) of the adrenal gland results as the endocrine system tries to react to the shortage of cortisol. The adrenal gland enlarges, but little extra cortisol can be produced. This hyperplasia results, however, in an excess of other steroid hormones, which have a masculinizing effect. As might be expected, masculinization is more of a problem for women than for men, and women with congenital adrenal hyperplasia are often born with ambiguous genitalia and grow to be larger, stronger, and hairier than most women. A more serious complication, however, is that of salt wasting. Since aldosterone plays a key role in the regulation of salt within the body, patients with inadequate aldosterone production may lose salt though excretion; this loss of salt can be life-threatening. It would be expected that a patient with congenital adrenal hyperplasia with salt wasting should be dependent upon medication for life. However, a 19-year-old woman with complete 21-hydroxylase deficiency has now been seen who discontinued her medication at the age of 18. The mere fact that this patient is alive indicates that the steroid metabolism involved in this disorder is more complex than has been previously suspected. After the patient stopped seeking medical care at age 15, she returned for reevaluation at the age of 19 (she had taken her medication until age 18). It was found that when the patient was on a low-salt diet, she excreted a normal amount of aldosterone every day. However, the patient also had a homozygous deletion in the CYP21 gene, which codes for the enzyme responsible for 21-hydroxylation of steroids. Therefore, within the adrenal gland, or some other tissue of the body, an alternative route of synthesis of aldosterone was taking place. This alternate synthesis served to keep the patient alive, when by conventional physiological theory she should have died. This patient also illustrates that the clinical course of a serious genetic disease cannot necessarily be predicted on the basis of checking one gene only. (Consumer Summary produced by Reliance Medical Information, Inc.)

Abnormalities, Aldosterone assay, Adrenal glands, Aldosterone, Virilism

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Prenatal treatment of congenital adrenal hyperplasia due to 21-hydroxylase deficiency

Article Abstract:

Congenital adrenal hyperplasia, also known as adrenogenital syndrome, is a congenital disorder usually caused by excess secretion of androgenic (masculinizing) hormones by the fetal adrenal gland or by medication containing male hormones. The symptoms include genital abnormalities, masculine secondary sex characteristics in females and accelerated puberty in males. This congenital disorder results from inherited mutations of the 21-hydroxylase genes. Prenatal diagnosis of congenital adrenal hyperplasia is possible, but effective methods of treating this condition prenatally have not been perfected. Treatment with glucocorticoids (adrenal cortical hormones) in the pregnant mother has been reported with mixed results. A case history of a 21-year-old woman who was pregnant with a female fetus that had adrenal hyperplasia is described. The disorder was detected in the fetus through amniotic fluid analysis and measurement of hormone levels. The mother was given dexamethasone (a synthetic glucocorticoid) in the sixteenth week of gestation with the intention of suppressing adrenal function and symptoms in the infant. This treatment was partially successful. The female infant was delivered at 36 weeks and exhibited slightly virilized female genitalia. Mild labial abnormalities and a slight enlargement of the clitoris were also observed. This baby was compared with 14 other female infants with congenital adrenal hyperplasia whose mothers were similarly treated with glucocorticoids during pregnancy. Wide variation in genital development was found in these infants. A number of factors that may have influenced these outcomes are discussed. In conclusion, the author recommends treating pregnant mothers with dexamethasone as early as the fifth week of pregnancy. Dosage should be carefully monitored to prevent drug side effects in the mother and fetus. (Consumer Summary produced by Reliance Medical Information, Inc.)

Analysis, Evaluation, Drug therapy, Dexamethasone, Prenatal diagnosis

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Congenital adrenal hyperplasia

Article Abstract:

The genetics, symptoms, diagnosis, and treatment of congenital adrenal hyperplasia are reviewed. This condition is caused by a deficiency of one of the enzymes involved in the biosynthesis of cortisol in the adrenal glands. More than 90% of cases are caused by a deficiency of steroid 21-hydroxylase. The condition can be diagnosed prenatally.

Care and treatment, Diagnosis, Genetic aspects

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