Background: We present a case of a neonate with life threatening hyponatraemia and hyperkalaemia, due pseudohypoaldosteronism, found to be caused by a novel mutation.
Objective and hypotheses: An 8-day-old girl presented with a short history of poor feeding and vomiting. She was born at term, to consanguineous parents. She was severely shocked and required fluid resuscitation. She had profound hyponatraemia and hyperkalaemia. She was admitted to PICU with continuous cardiac monitoring. Electrolyte abnormalities improved over 48 h.
Method: We discuss a diagnostic algorhythm; differentials considered included salt-wasting congenital adrenal hyperplasia, aldosterone synthase deficiency and adrenal hypoplasia congenita; resulting in aldosterone deficiency.
Results: Blood testing revealed a markedly elevated aldosterone (45 200 pmol/l) and renin (>34 ng/ml per h), leading to a diagnosis of pseudohypoaldosteronism. Pseudohypoaldosteronism is a rare syndrome of resistance to aldosterone, caused by decreased function of ENaC (epithelial sodium channel) and manifested by salt wasting, which can lead to shock and death. Genetic testing in this case has found a novel mutation in SCNN1A gene, which has autosomal recessive inheritance and is characterized by a permanent defect of ENaC, affecting all aldosterone target organs (kidney, salivary and sweat glands, respiratory tract, and colon).
Conclusion: This is the first case of pseudohypoaldosteronism with this mutation, in Northern Ireland and illustrates the pertinent investigations and important differential diagnoses to consider in infants with severe hyponatraemia and hyperkalaemia.
20 - 22 Sep 2014
European Society for Paediatric Endocrinology