Renal & Urology
AKI, electrolytes, UTIs and urological emergencies.
Use as a study guide only. These notes are part of a free open-access medical education (FOAMed) project and may contain errors or outdated information. Always verify against current guidelines (e.g. eTG, RACGP, local health district policies) and reputable sources before applying anything to patient care. See the full disclaimer.
Clinical pearls & learnings
Tips and tricks collected over the years — a living list that grows with every rotation. Use as a study guide only and check current guidelines before acting on anything.
Sodium & electrolytes
Getting sodium correction right
Sodium correction — the rule and the rescue
| Scenario | What to do | Watch for |
|---|---|---|
| Any sodium derangement | Aim for a change of no more than ~10 mmol/L in 24 hours | Over-correction in either direction |
| Hypernatraemia | Correct slowly with gentle rehydration | Rapid correction risks cerebral oedema |
| Symptomatic hyponatraemia (seizures, reduced consciousness) | Hypertonic 3% saline, typically 3mL/kg | Frequent sodium checks |
| SIADH | Fluid restrict and treat the underlying cause | Reserve 3% saline for symptomatic patients only |
Consider the causes of a low sodium in children specifically: SIADH, water intoxication, and over-dilution of infant formula — a real and under-recognised cause in families under financial stress. Rehydrate with an appropriate electrolyte solution and address the social cause alongside the biochemistry.
Diabetes insipidus sits at the opposite end — polyuria with rising sodium. Do not assume every deranged sodium in an unwell child is dehydration; measure paired serum and urine osmolality before committing to a treatment direction.