337dexamethasone 0.25 mg/day and fludrocortisone 150 μg/day, and with this
therapy, 17(OH)P decreased to 40 ng/ml. Hydrocortisone was added at a daily
dose of 10 mg (in three divided doses) along with dexamethasone and fludro-
cortisone (Fig. 10.1 ).
10.2 Stepwise Analysis
The index patient presented at the age of 15 days with features of salt crisis. The dif-
ferential diagnosis of recurrent episodes of vomiting in a neonate raises a suspicion
of neonatal sepsis, gastroenteritis, and hypertrophic pyloric stenosis. However, all
these disorders are associated with hyponatremia and hypokalemia. The concurrent
presence of hyponatremia with hyperkalemia in an infant with recurrent episodes of
vomiting suggests the possibilities of CAH, congenital adrenal hypoplasia, and pseu-
dohypoaldosteronism. The index patient had very high serum 17(OH)P and hyperka-
lemia, which conclusively established the diagnosis of salt-wasting variant of
classical CAH due to 21α-hydroxylase defi ciency. Serum 17(OH)P >100 ng/ml in an
infant with salt crisis obviates the need for ACTH stimulation test. The other salt-
wasting variant of CAH associated with mild elevation of 17(OH)P includes 3βHSD
type 2 defi ciency which is usually associated with genital ambiguity in both genders.
The salt crisis in neonates with CAH usually manifests at 1–2 weeks of life despite
the enzyme defi ciency present since birth. This occurs because of transplacental
abFig. 10.1 ( a ) A 13-year-old female with CAH due to 21α-hydroxylase defi ciency. ( b ) External
genitalia shows isolated clitoromegaly with posterior labial fusion
10 Congenital Adrenal Hyperplasia