343- What are the differential diagnoses to be considered in a neonate with salt -
wasting crisis?
One of the characteristic features of salt-wasting crisis is vomiting and hypo-
tension. However, neonates with congenital hypertrophic pyloric stenosis, gas-
tric volvulus, gastroenteritis, sepsis, and meningitis can also present with
intractable vomiting and hypotension. All these disorders are characterized by
the presence of hypokalemia, and the presence of hyperkalemia and metabolic
acidosis in a newborn with vomiting and hypotension should alert the possibil-
ity of salt-wasting crisis due to CAH, congenital adrenal hypoplasia, congenital
hypoaldosteronism (aldosterone synthase defi ciency), or pseudohypoaldoste-
ronism (aldosterone resistance).- Why is hypotension severe in salt - wasting children with CAH?
Aldosterone defi ciency manifests as salt-wasting; however, the manifestations
of salt-wasting are amplifi ed by the coexisting cortisol defi ciency present in
patients with CAH. This is because cortisol is required for maintenance of
vasoreactivity to circulating vasopressors including angiotensin II and cate-
cholamines. Cortisol is also essential for the synthesis of catecholamine in
adrenal medulla; hence, catecholamine insuffi ciency also contributes to hypo-
tension in patients with CAH. In addition, the accumulation of 17(OH)P which
has mineralocorticoid antagonistic properties also contribute to severe
hypotension.- Is salt - wasting crisis more common in females with CAH due to 21α - hydroxylase
defi ciency?
No. Salt-wasting crisis due to CAH is more commonly diagnosed in 46,XX
newborns as compared to 46,XY neonates. This is because during an episode of
salt crisis, the presence of genital ambiguity in a 46,XX newborn alerts the
clinician to consider a possibility of CAH, whereas the diagnosis of salt crisis
due to CAH is often missed in a 46,XY neonate due to the absence of genital
ambiguity, and many of 46,XY neonate succumb to salt crisis. The presence of
genital hyperpigmentation and hyperkalemia are the clues to suspect CAH in a
46,XY neonate with salt-wasting crisis.- How to approach a neonate with salt-wasting crisis?
Any child presenting with vomiting, dehydration, and hypotension should be
suspected to have salt crisis, and serum electrolytes, blood glucose, and blood
gas analysis should be urgently performed in these children. The presence of
hyperkalemia and metabolic acidosis suggest a diagnosis of salt- wasting crisis.10 Congenital Adrenal Hyperplasia