Background Hyponatraemia in children is not uncommon. The list of causes is long. It needs prompt investigation and management.

Case Patient presented at the age of 2 years with diarrhea and vomiting. On admission, he was in hypovolaemic shock. He was failing to thrive and had previous admission with similar presentation. Investigation revealed significant hyponatraemia, hyperkalaemia and metabolic acidosis. He was promptly resuscitated with intravenous fluids. Further evaluation revealed very low aldosterone, very high renin levels and normal 17 OH progesterone. He was diagnosed as a case of aldosterone synthase deficiency and was started on Flouninef.

Conclusion Aldosterone synthase deficiency is a rare cause of hyponatraemia but should be considered in the differential diagnosis especially as management is relatively simple.