Electrolyte disorders: potassium, magnesium and phosphate
Working up and replacing low potassium, magnesium and phosphate, recognising refeeding syndrome, and handling the high levels that matter.
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Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Low potassium, magnesium and phosphate travel together, especially in diarrhoea, alcohol use, diuretic use, DKA treatment and refeeding. Measure all three when you find one.
- Fix magnesium first. Hypokalaemia and hypocalcaemia both resist correction while magnesium is low.
- In hypokalaemia, decide between a shift, a GI loss and a renal loss. Spot urine potassium and the blood pressure sort most cases.
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Sources
- Fluid and electrolyte disorders (Therapeutic Guidelines)AU/NZTherapeutic Guidelines Ltd
- Potassium homeostasis and management of dyskalemia in kidney diseases: conclusions from a KDIGO Controversies ConferenceKDIGO (Clase et al., Kidney Int 2020;97:42-61), 2020
- UK Kidney Association clinical practice guideline: treatment of acute hyperkalaemia in adultsUK Kidney Association, Updated July 2026
- Guideline 11.5: medications in adult cardiac arrestAU/NZAustralian and New Zealand Committee on Resuscitation (ANZCOR), April 2025
- The Australasian Society of Parenteral and Enteral Nutrition: consensus statements on refeeding syndromeAU/NZNutrition & Dietetics (Matthews-Rensch et al., 2025;82:128-42), 2025
- Nutrition support for adults: oral nutrition support, enteral tube feeding and parenteral nutrition (CG32)National Institute for Health and Care Excellence, 2006, updated 2017
- ASPEN consensus recommendations for refeeding syndromeAmerican Society for Parenteral and Enteral Nutrition (da Silva et al., Nutr Clin Pract 2020;35:178-95), 2020
- Effects of iron isomaltoside vs ferric carboxymaltose on hypophosphatemia in iron-deficiency anemia: two randomized clinical trials (PHOSPHARE-IDA)Wolf et al., JAMA 2020;323:432-43, 2020
- Last updated
- 14 November 2026
What changed
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