Introduction: Severe hypernatremia in infants is uncommon and usually linked to dehydration or feeding errors. When sodium rises rapidly despite appropriate fluid therapy, rarer causes such as salt poisoning must be considered. This case illustrates the importance of early suspicion, safeguarding, and multidisciplinary management.Case Summary: A 10-week-old male infant was admitted with lethargy and poor feeding. Initial sodium was 168 mmol/L, rising to 198 mmol/L within 48 hours despite controlled IV fluids. Urine sodium exceeded 200 mmol/L, and osmolality was preserved, ruling out dehydration and diabetes insipidus. The clinical course, disproportionate biochemical findings, and stable weight raised strong suspicion of exogenous salt administration. White crystalline particles found in the infant’s cubicle were confirmed to be salt. The child deteriorated with seizures and respiratory compromise, requiring PICU transfer. Neuroimaging revealed subdural and subarachnoid haemorrhages. Multidisciplinary input (renal, metabolic, PICU, safeguarding, social services) was initiated promptly. An interim care order was granted; the infant was discharged under foster care with neurodevelopmental follow-up.Learning Points / Conclusions- Rapidly rising sodium despite controlled fluid therapy should raise suspicion for salt poisoning.- Urine sodium and osmolality are critical in differentiating causes of hypernatremia.- Suspected non-accidental injury requires early safeguarding involvement and forensic evidence preservation.- Multidisciplinary coordination is essential for both medical management and child protection.
