RESUMO
We present a case of a male neonate who experienced a 13.5% weight loss at 96 hours of life, despite receiving adequate calorie intake and exhibiting no feeding difficulties. The pregnancy was uneventful, and maternal serological investigation was normal. A routine ultrasound at 34 weeks of gestational age revealed late oligohydramnios. The neonate was delivered at 35 weeks of gestational age by forceps, weighing 2600 g. Physical examination disclosed bilateral cryptorchidism. Laboratory studies unveiled acute kidney injury (AKI) with hyperkalaemia. Renal ultrasound revealed bilateral hydronephrosis and renal dysplasia with pyelocalyceal dilatation. Despite early recognition and treatment, the newborn developed chronic kidney disease (CKD). AKI is an important and under-recognised cause of significant neonatal weight loss.This case underscores the significance of considering AKI as a potential and under-recognised cause of neonatal weight loss. It emphasises the importance of maintaining a high clinical suspicion for early AKI diagnosis to mitigate the risk of progression to CKD.