ESPE Abstracts

Background: Secondary pseudohypoaldosteronism (PHA) type 1 is an uncommon salt losing condition of infancy caused by transient resistance of the mineralocorticoid receptors (MR) of the renal tubule to aldosterone. This can be secondary to urinary tract infection (UTI), urinary tract malformation (UTM) or obstructive uropathy. Ninety percent of reported cases present before 3 months and nearly all are under 7 months of age.

Objective and hypotheses: The commonest clinical presentation is failure to thrive and salt-wasting, associated with metabolic acidosis. The initial presentation may mimic that of congenital adrenal hyperplasia (CAH) with shock, acidosis and hyperkalaemia. Definitive diagnosis can be difficult, but is crucial to guide management. The urinary steroid profile (USP) has a very specific pattern in PHA, with increase of both corticosterone and aldosterone metabolites. This is useful in the exclusion of salt wasting forms of CAH and aldosterone synthase defects. PHA secondary to a UTI is further distinguished by a relative increase in urinary cholesterol. Normalisation of the USP following treatment of the underlying cause confirms resolution of secondary PHA.

Method: We report findings in two infants with secondary PHA type 1 who presented at 5 and 8 weeks with failure to thrive, profound salt wasting and metabolic acidosis. The two cases had confirmed UTI and UTM. We describe clinical course, management and follow up over a 1-year period focusing on the use of the urinary steroid profile (USP) for the investigation and follow-up of both patients.

Results: Secondary PHA type 1 is a transient salt losing condition of infancy and the USP offers a reliable non-invasive method for definitive diagnosis.

Conclusion: We report a new finding that PHA secondary to a UTI can be further distinguished by a relative increase in urinary cholesterol, with normalisation following treatment of the underlying cause to confirm resolution.