Pediatric emergency medicine trisk 1884 1884
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Inborn errors of adrenal steroid biosynthesis are grouped under the term congenital adrenal
hyperplasia (CAH). Two major modes of presentation occur in early infancy and require
prompt diagnosis and treatment: acute salt-losing crisis and ambiguous genitalia ( Table 89.6
). CAH may also present in children as precocious virilization. This form of CAH warrants
investigation, but it does not require emergency management. The most common form of CAH
presenting in infancy is 21-hydroxylase deficiency, which is recessively inherited and accounts
for 90% of all cases. Clinically apparent salt wasting develops in approximately two-thirds of
affected patients. In the United States, the incidence of 21-hydroxylase deficiency is
approximately 1 in 15,000 live births. The enzymes 21-hydroxylase, 11β-hydroxylase, 3βhydroxysteroid dehydrogenase, and 20,22-desmolase are involved in the production of both
cortisol and aldosterone ( Fig. 89.1 and Table 89.6 ). Because the hypothalamic–pituitary axis
is under feedback control by cortisol, the lack of production of this hormone caused by the
enzyme deficiency results in a significant increase in ACTH. In turn, ACTH stimulates the
adrenal to increase steroid hormone production. Because cortisol synthesis is impaired, the
precursors of cortisol accumulate significantly. The symptoms and signs characteristic of each
enzymatic deficiency reflect either the absence of cortisol or aldosterone or the accumulation
of their precursors.
Impairment of mineralocorticoid synthesis by 21-hydroxylase, 3β-hydroxysteroid
dehydrogenase, and 20,22-desmolase deficiency can result in salt wasting. Although 11βhydroxylase deficiency also blocks aldosterone production, the immediate precursor to the
block, deoxycorticosterone, has potent mineralocorticoid activity. Thus, instead of developing
salt loss, patients with this enzyme defect often develop hypertension during childhood.
Androgenic compounds accumulate in 21-hydroxylase and 11β-hydroxylase deficiencies.
Females with these defects are virilized in utero and are born with ambiguous genitalia;
therefore, females are often identified in the newborn period. Some female infants are so
virilized that they are mistaken as males with bilateral cryptorchidism. Males have normal
genital development; therefore, the diagnosis is generally missed until they present with saltwasting crisis during infancy or with evidence of precocious puberty during childhood.
Deficiency of 3β-hydroxysteroid dehydrogenase leads to underproduction of testosterone.
Boys with this deficiency are undervirilized because only weak androgens are produced,
whereas girls are mildly virilized because of these weak androgens. Lack of cortisol renders
the patient more susceptible to hypoglycemia and reduces the tolerance to severe stress, such
as dehydration.
Clinical Considerations
Clinical Recognition
CAH may manifest at birth with the discovery of ambiguous genitalia, between 2 and 5 weeks
of age when the baby presents with acute salt-losing crisis, or during childhood with the onset
of precocious puberty. The affected child may come to the ED for any of these reasons.
Although all US states now screen newborns for CAH, the results may not be available for 2 to
3 weeks and the acute salt-losing crisis may occur before this time. Furthermore, the report of
an abnormal test result may precipitate a visit to the ED: Unless the child is ill, consultation
with a pediatric endocrinologist is highly recommended before initiating therapy. Salt wasting
