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Hypernatraemic dehydration – breastfed — RACP Paediatrics MCQ

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HardNeonatalHypernatraemic dehydration – breastfedRACP Paediatrics

A 4-day-old exclusively breastfed term neonate has lost 12% of birth weight. The infant is sleepy, has reduced urine output (2 wet nappies in 24 hours), and has a serum sodium of 155 mmol/L. Bilirubin is 280 µmol/L. What is the most likely diagnosis?

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Correct answer: E — Hypernatraemic dehydration

Weight loss >10% in a breastfed neonate with hypernatraemia (Na >145) and reduced urine output indicates hypernatraemic dehydration from inadequate breast milk intake. This is a serious condition that can cause intracranial haemorrhage and seizures. Management includes gradual rehydration (avoid rapid sodium correction), supplemental feeds, and lactation support. Sodium should not be corrected faster than 0.5 mmol/L/hr.

Reference: RCH Melbourne – 2023 – Neonatal Dehydration CPG; RACP Paediatric Curriculum – Neonatology