Adrenogenital syndrome

Description, Causes and Risk Factors adrenogenital syndrome:

Adrenal cortex is divided into three distinct zones - the outer zona glomerulosa, the middle zona fasciculata, and the inner zona reticularis - defined by their different cellular arrangements. They are functionally distinct zones, i.e. mineralocorticoids are synthesized in the zona glomerulosa, glucocorticoids are produced by the zona fasciculata/reticularis, and androgenic steroids are synthesized in the zona reticularis.

Cortisol is synthesized from cholesterol in the zona fasciculata of the adrenal cortex. This process requires five enzymatic conversions (five steps): cleavage of the cholesterol side chain to yield pregnenolone (cholesterol desmolase enzyme), 17-alpha hydroxylation to yield 17 hydroxypregnenolone (17-OH-pregnenolone), 3-beta-dehydrogenation to yield 17-hydroxyprogesterone, and successive hydroxylations at the 21 and 11 beta positions resulting in cortisol. Steroid 21-hydroxylase (CYP21, also termed CYP21A2 and P450c21) is a cytochrome P-450 enzyme located in the endoplasmic reticulum. This enzyme is involved in the biosynthesis of both cortisol and aldosterone. It catalyzes the conversion of 17-hydroxyprogesterone to 11-deoxycortisol, a precursor of cortisol, and the conversion of progesterone to deoxycorticosterone, a precursor of aldosterone. Owing to this loss of enzyme function, patients with 21-hydroxylase deficiency cannot synthesize cortisol efficiently, and as a result, the adrenal cortex is stimulated by adrenocorticotropin (ACTH) and overproduces cortisol precursors. Some of these precursors are diverted to the biosynthesis of sex hormones, which may cause signs of androgen excess, including ambiguous genitalia in newborn girls and rapid postnatal growth in both sexes. Concomitant aldosterone deficiency may lead to salt wasting with consequent failure to thrive, hypovolemia, and shock.

All of the forms of adrenogenital syndrome are caused by genetically induced enzyme deficiencies in the pathways that produce steroid hormones. Deficiency of the enzyme 21-hydroxylase accounts for 95% of affected patients.

Causes & Risk Factors:

Tumors of the adrenal cortex are frequent. They are reported in 2% of all autopsies, with the most common lesion being a benign adenoma. Approximately 80% of adrenal cortical adenomas are not hormonally active. The remainder produces excess of cortisol (manifesting clinically as Cushing syndrome), or excess of aldosterone (manifesting clinically as Conn syndrome). Adrenocortical adenomas are not likely to produce androgens, but adrenocortical carcinomas do. Adrenocortical carcinomas are uncommon tumors (1% of all adrenal cortical masses). They are hormonally active in about 60% of cases, and most of them secrete androgens, clinically presenting with virilization syndromes.

• Congenital adrenal hyperplasia is a group of autosomal recessive disorders resulting from the impaired enzymatic action of one of the enzymes required for the synthesis of cortisol or aldosterone in the adrenal cortex. The most frequent disorder is steroid 21-hydroxylase deficiency, accounting for more than 90 % of cases. The second most frequent is 11 beta-hydroxylase deficiency accounts for 5-8% of all congenital adrenal hyperplasia cases.

• Another disorder, 17-hydroxylase deficiency accounts for less than 1% of cases of congenital adrenal hyperplasia. Blocks in cortisol or aldosterone synthesis result in some degree of cortisol deficiency, aldosterone deficiency, or both. On the other hand, blocks in cortisol synthesis impair the negative feedback control of the adrenocorticotropic hormone (ACTH) secretion, which leads to chronic stimulation of the adrenal cortex by ACTH and adrenal cortical hyperplasia. The enzyme deficiencies in adrenogenital syndrome (congenital adrenal hyperplasia) act as a dam behind which steroid precursors accumulate. They are then shunted through the uninhibited pathways and result in excessive synthesis and secretion of adrenal androgens.

Symptoms:

Symptoms will vary, depending on the type someone has and their age when the disorder is diagnosed.

Children with milder forms may not have signs or symptoms and may not be diagnosed until as late as adolescence.

• Girls with a more severe form often have abnormal genitals at birth and may be diagnosed before symptoms appear.

• Boys will appear normal at birth even if they have a more severe form.

• In children with the more severe form of the disorder, symptoms often develop within 2 or 3 weeks after birth.

• Dehydration.

• Electrolyte changes (abnormal levels of sodium and potassium in the blood).

• Abnormal heart rhythm.

• Abnormal menstrual periods or failure to menstruate.

• Excessive hair growth.

• Some enlargement of the clitoris.

• Deepening voice.

• Enlarged penis but normal testes.

• Well-developed muscles.

Diagnosis:

Common tests include:

Serum electrolytes.

• Aldosterone.

• Renin.

• Cortisol.

• Imaging: X-rays may be helpful.

• Genetic tests can help diagnose or confirm the disorder, but that are rarely needed.

Treatment:

Treatment of this condition involves hormone replacement. Treatment is monitored by measures of blood salt composition (electrolytes), by suppression of overly-rapid sexual maturation, and by monitoring of the skeletal maturation rate by bone age testing.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.