Three infants (age 1.5, 4 and 7 months) presented with vomiting, hyponatremia and hyperkalaemia suggestive of a salt-losing congenital adrenal condition. Diagnostic endocrine bloods were taken and adrenal steroid therapy was started. The infants were subsequently found to have raised plasma aldosterone and renin levels due to pyelonephritis and structural anomalies of the kidneys, demonstrating secondary aldosterone resistance.
Conclusion: Establishing the diagnosis of congenital adrenal disorders is essential in a baby who develops a salt-losing crisis in the first few weeks of life. However, pyelonephritis should be considered and can be rapidly excluded in any infant presenting with a salt-losing crisis with hyponatremia and hyperkalaemia, in particular, outside the neonatal period. Only then should an endocrine cause for this presentation be considered and treatment commenced.