ESPE Abstracts

Background: Pseudohypoaldosteronism is a rare condition of renal or systemic resistance to aldosterone, divisible into separate clinical presentations, each with a distinct physiological and genetic basis. Transient pseudohypoaldosteronism is a secondary form, characterised by reduced glomerulofiltration rate. It has been described in infants with obstructive uropathy and urinary tract infections.

Method: We present five cases, presenting in infancy with sepsis and significant hyponatraemia, where underlying obstructive uropathy was subsequently discovered.

Results: One female and four males presented unwell with vomiting and dehydration, between 26 days and 6 months old. All had normal antenatal scans. All were recognised as a ‘sick child’ before initiating investigations. Serum sodium at presentation ranged between 113 and 120 mmol/l, with potassium above 6 mmol/l. Serum osmolality was normal in presence of reduced urine osmolality. In all cases, random serum cortisol was >1000 nmol/l. Unfortunately, aldosterone was not measured in our patients. Urinary tract infection was confirmed by pyuria. Organisms cultured included coliforms. One case was complicated by infective urinary ascites which grew Citrobacter koseri. Significant obstructive uropathy was demonstrated by ultrasound scan (USS), and further characterised by micturating cysto-urethrogram after the acute period. Management involved fluid resuscitation and intravenous antibiotics. One case, with an initial delay in the diagnosis of obstructive uropathy, was complicated by renal parenchymal abscesses and infective urinary ascites secondary to renal tract rupture. This required drainage and urostomy formation. The others made good recoveries, without further biochemical abnormalities.

Conclusion: In infants presenting unwell with unexplained hyponatraemia and hyperkalaemia, differentials to be considered include congenital adrenal hyperplasia, pseudohypoaldosteronism secondary to obstructive uropathy or pyelonephritis, and biochemical disturbances secondary to pyeloric stenosis. With this case series, we highlight the importance of early appropriate investigations including USS in these children to avoid significant morbidity associated with delayed diagnosis of obstructive uropathy undetected by antenatal scans.