Critical hyponatraemia secondary to severe bilateral renal artery stenosis requiring intensive care – an unusual aetiopathogenesis for a common problem

A woman in her early sixties presented to the emergency department with an altered level of consciousness and severe hypertension (blood pressure 197/111 mmHg) on a background of Grave's disease, osteoporosis and hypertension. She was intubated following prolonged seizure activity attributed to critical hyponatraemia (serum sodium 108 mmol/L). Abnormal renal function (estimated glomerular filtration rate 51 ml/min per 1.73m²) was also identified on admission. She was transferred to the intensive care unit for further investigation and management of hypertension and hyponatraemia, where she made an excellent recovery and a unifying diagnosis of bilateral renal artery stenosis was made. Renal artery stenosis has been previously described with chronic and unilateral presentations not requiring intensive care support. This case report describes the pathophysiology of this previously unreported presentation of severe symptomatic hyponatraemia and hypertension due to bilateral renal artery stenosis and the challenges faced in intensive care to determine the diagnosis.