Adrenogenital syndrome
Adrenogenital syndrome: Excerpt from Professional Guide to Diseases (Eighth Edition)
Adrenogenital syndrome results from disorders of adrenocortical steroid biosynthesis. This syndrome may be inherited (congenital adrenal hyperplasia [CAH]) or acquired, usually as a result of an adrenal tumor (adrenal virilism). Salt-losing CAH may cause fatal adrenal crisis in neonates.
Causes and incidence
CAH is transmitted as an autosomal recessive trait that causes deficiencies in the enzymes needed for adrenocortical secretion of cortisol and, possibly, aldosterone. Compensatory secretion of corticotropin produces varying degrees of adrenal hyperplasia. In simple virilizing CAH, deficiency of the enzyme 21-hydroxylase results in underproduction of cortisol. In turn, this cortisol deficiency stimulates increased secretion of corticotropin, producing large amounts of cortisol precursors and androgens that don’t require 21-hydroxylase for synthesis.
In salt-losing CAH, 21-hydroxylase is almost completely absent. Corticotropin secretion increases, causing excessive production of cortisol precursors, including salt-wasting compounds. However, plasma cortisol and aldosterone levels — both dependent on 21-hydroxylase — fall precipitously and, in combination with the excessive production of salt-wasting compounds, precipitate acute adrenal crisis. Corticotropin hypersecretion stimulates adrenal androgens, possibly even more than in simple virilizing CAH, and produces masculinization. Other rare CAH enzyme deficiencies exist and lead to increased or decreased production of affected hormones.
CAH is the most prevalent adrenal disorder in infants and children; simple virilizing CAH and salt-losing CAH are the most common forms. Acquired adrenal virilism is rare and affects twice as many females as males. About 1 in 10,000 to 18,000 are born with CAH.
Signs and symptoms
The neonatal female with simple virilizing CAH has ambiguous genitalia (enlarged clitoris, with urethral opening at the base; some labioscrotal fusion) but normal genital tract and gonads. As she grows older, signs of progressive virilization develop: early appearance of pubic and axillary hair, deep voice, acne, and facial hair. The neonatal male with this condition has no obvious abnormality; however, at prepuberty he shows accentuated masculine characteristics, such as deepened voice and an enlarged phallus, with frequent erections. At puberty, females fail to begin menstruation, and males have small testes. Both males and females with this condition may be taller than other children their age as a result of rapid bone and muscle growth, but because excessive androgen levels hasten epiphyseal closure, abnormally short adult stature results. (See Acquired adrenal virilism.)
Salt-losing CAH in females causes more complete virilization than the simple form and results in development of male external genitalia without testes. Because males with this condition have no external genital abnormalities, immediate neonatal diagnosis is difficult, and is commonly delayed until the infant develops severe systemic symptoms. Characteristically, such an infant is apathetic, fails to eat, and has diarrhea; he develops symptoms of adrenal crisis in the first week of life (vomiting, dehydration from hyponatremia, hyperkalemia). Unless this condition is treated promptly, dehydration and hyperkalemia may lead to cardiovascular collapse and cardiac arrest.
Diagnosis
Physical examination revealing pseudohermaphroditism in females or precocious puberty in both sexes strongly suggests CAH. (See Hermaphroditism.)
Confirming diagnosis The following laboratory findings confirm the diagnosis: elevated plasma 17-ketosteroids (17-KS), which can be suppressed by administering oral dexamethasone; elevated urinary levels of hormone metabolites, particularly pregnanetriol; elevated plasma 17-hydroxyprogesterone level; and normal or decreased urinary levels of 17-hydroxycorticosteroids. Elevated dehydroepiandrosterone sulfate is present.
Adrenal hypofunction or adrenal crisis in the first week of life suggests salt-losing CAH. Hyperkalemia, hyponatremia, and hypochloremia with excessive urinary 17-KS and pregnanetriol and decreased urinary aldosterone levels confirm it.
Treatment
Simple virilizing CAH requires correction of the cortisol deficiency and inhibition of excessive pituitary corticotropin production by daily administration of cortisol. Treatment returns androgen production to normal levels. Measurement of urinary 17-KS levels determines the initial dose of cortisone or hydrocortisone; this dose is usually large and is given I.M. Later dosage is modified according to decreasing urinary 17-KS levels. Infants must continue to receive cortisone or hydrocortisone I.M. until age 18 months; after that, they may take it orally.
PEDIATRIC TIP The infant with salt-losing CAH in adrenal crisis requires immediate I.V. sodium chloride and glucose infusion to maintain fluid and electrolyte balance and to stabilize vital signs. If saline and glucose infusion doesn’t control symptoms while the diagnosis is being established, desoxycorticosterone I.M. and hydrocortisone I.V. are necessary. Later, maintenance includes mineralocorticoid (desoxycorticosterone, fludrocortisone, or both) and glucocorticoid (cortisone or hydrocortisone) replacement.
Sex chromatin and karyotype studies determine the genetic sex of patients with ambiguous external genitalia. Females with masculine external genitalia require reconstructive surgery, such as correction of the labial fusion and of the urogenital sinus. Surgery is usually scheduled between ages 1 and 3, after the effect of cortisone therapy has been assessed.
Special considerations
Suspect CAH in infants hospitalized for failure to thrive, dehydration, or diarrhea, as well as in tall, sturdy-looking children with a record of numerous episodic illnesses.
❑ When caring for an infant with adrenal crisis, keep the I.V. line patent, infuse fluids, and give steroids, as ordered. Monitor body weight, blood pressure, and serum electrolyte levels carefully, especially sodium and potassium levels. Watch for cyanosis, hypotension, tachycardia, tachypnea, and signs of shock. Minimize external stressors.
❑ If the child is receiving maintenance therapy with steroid injections, rotate I.M. injection sites to prevent atrophy; tell parents to do the same. Teach them the possible adverse effects (cushingoid symptoms) of long-term therapy. Explain that maintenance therapy with hydrocortisone, cortisone, or the mineralocorticoid fludrocortisone is essential for life. Warn parents not to withdraw these drugs suddenly because potentially fatal adrenal hypofunction will result. Instruct parents to report stress and infection, which require increased steroid dosages.
❑ Monitor the patient receiving desoxycorticosterone or fludrocortisone for edema, weakness, and hypertension. Be alert for significant weight gain and rapid changes in height because normal growth is an important indicator of adequate therapy.
❑ Instruct the patient to wear a medical identification bracelet indicating that she’s on prolonged steroid therapy and providing information about dosage.
❑ Help the parents of a female infant with male genitalia to understand that she’s physiologically a female and that this abnormality can be surgically corrected. Arrange for counseling if necessary.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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