Document resource
Infants presenting with life-threatening hyponatraemia and hyperkalaemia present a diagnostic conundrum that can reflect abnormally low aldosterone production, for example, congenital adrenal hyperplasia (CAH), or renal resistance to aldosterone, for example, infected urinary tract malformations. Although incidence figures for individual conditions exist, there are no data regarding this characteristic biochemical pattern and underlying cause. We aimed to estimate the incidence, characteristics and 1 month outcome of term infants <12 months old presenting with both low sodium (<130 mmol/L) and high potassium (>5.5 mmol/L) in Wales. This study was submitted to, approved by and conducted by the Welsh Paediatric Surveillance Unit, which collected data from reporting paediatricians during 2021–2023. To enhance reporting, we also contacted hospital biochemists and tertiary endocrinology specialists. After case confirmation, reporters were sent a questionnaire regarding patient characteristics, diagnosis, electrolytes, renin, aldosterone and 17-hydroxyprogesterone concentrations, time to sodium normalisation and outcome at 1 month. Wales does not undertake newborn screening for CAH.