see also: [[hyponatremia]] - [RCH hyponatraemia](https://www.rch.org.au/clinicalguide/guideline_index/Hyponatraemia/) # causes **dehydration** - GI lossses - [[Gastroenteritis]] - secreatory/osmotic diarrhoea - skin losses - cystic fibrosis - [[Burns]] - abdominal 3rd spacing - [[hyperglycaemia|hyperglycemia]] - cerebral salt wasting - renal tubular disorders - [[Adrenal insufficiency]] - [[Blood gas#Metabolic alkalosis]] **euvolaemic** - increased ADH secretion (**SIADH**) - pulmonary: pneumonia, [[Bronchiolitis]], mechanical ventilation - CNS: [[Meningitis]], injury, tumour - post-operative, trauma, *pain* - endocrine: [[Hypothyroidism|hypothyroid]], [[Cushing's disease]] - *administration of enteral hypotonic fluids* - dilute formula - oral rehydration solutions - excessive water intake - psychogenic polydipsia - medications - chemotherapy - antiepileptics [[Valproate]], [[carbamazepine]] - vasopressin **fluid overload** - excess IV fluid - nephrotic syndrome - cirrhosis - heart failure - acute/chronic renal failure - obstructive uropathy # management algorithm **Ix** - Paired serum and urine osmolality - Urinary sodium - BSL (if hyperglycaemia present in addition to hyponatraemia see DKA) - Corrected sodium in hyperglycaemia = serum Na + (BSL-5)/3 - Consider blood gas if significantly unwell **Treatment** - Management is determined by ==presence of seizures/altered conscious state== and ==fluid status== - The target rate of serum sodium correction is ==6-8 mmol/L in 24 hours== (*unless seizing*, see flowchart below) - All children should have a strict fluid balance including weight - Treat the underlying cause ![[Pasted image 20240221115710.png]]