- Clinical complications that can occur as a result of fluid and electrolyte shifts during nutritional rehabilitation of malnourished patients.
- Key electrolyte abnormalities are: hypophosphatemia, hypokalemia & hypomagnesemia. Hypophosphatemia usually drops first, subsequently causing a decline to potassium and magnesium levels.
- Involve a dietician and/or senior registrar before commencement of IV electrolytes
|Electrolyte||Phosphate (0.8 – 1.5 mmol/L) (1)||Potassium (3.5 – 5.0 mmol/L) (2)||Magnesium (0.8 – 1.1 mmol/L) (3)|
|Mild||0.5-0.8 mmol/L||3.0 – 3.5 mmol/L||0.7 – 0.8 mmol/L|
|Moderate||0.3 – 0.5 mmol/L||2.5 – 3.0 mmol/L||0.4 – 0.6 mmol/L|
|Severe||<0.3 mmol/L||<2.5 mmol/L||<0.4 mmol/L|
- Severely malnourished and dehydrated patients at a low body weight e.g. Oncology patients, malnourished elderly patients and patients who have not eaten for many days (e.g. anorexia nervosa, chronic alcoholism)(4).
- Drops in electrolytes can be extremely rapid and aggressive replacement may be required.
Patients at high risk:
- BMI < 16
- Loss of > 15% body weight in last 3-6 months
- Minimal nutritional intake for 10 days
- Low concentrations of phosphate, potassium or magnesium before reintroduction of nutrition
An increase in carbohydrate (glucose) consumption leads to a rapid surge in insulin levels that result in an intracellular shift of several electrolytes (phosphate, potassium & magnesium).
Clinical features #
Clinical features are usually only present when the patient has severe electrolyte derangements. Ensure to perform a detailed cardiovascular & neurological assessment(4).
|History & examination||Muscle weaknessRespiratory failure Seizures Delirium Areflexic paralysis||Muscle weaknessConstipationArrhythmia & ECG changes||Muscle weaknessTremorTetanySeizures Arrhythmia|
- Thiamine deficiency: Wernicke-Korsakoff encephalopathy
- Sodium retention: peripheral and pulmonary oedema
- *Frequency of investigations will depend on severity of derangements but monitor UEC, CMP, BSL 6-hourly for 24-48 hours with onset of refeeding (4).
|VBG||Immediate Serum K+ (↓)BGL (↑)|
|UEC||Serum K+ (↓)Serum Na+(↑) Creatinine (↑)|
|CMP||Serum Mg (↓)Serum PO4- (↓)|
|B12, folate, iron & Zn||Nutritional assessment|
|ECG (1,2,3)||Look for ECG abnormalities that may result from critically low levels of K+, Mg & PO4-: |
Ventricular tachyarrhythmias Prolonged QT ST depression T wave flattening Prolonged PR
|24-hour urine phosphate excretion (1)||<100mg or FEPO4 5% indicates appropriate low renal phosphate excretion, caused by:Internal redistribution |
e.g. refeeding syndrome Decreased intestinal absorption
|Creatine Kinase||Rhabdomyolysis secondary to hypophosphatemia|
All management decisions should be made in consultation with a dietician(5). #
- Introduce nutritional rehabilitation slowly (e.g. 30-50% of estimated caloric requirement) and gradually increase to patients requirement (e.g. 5-7 days) as per dietician request
- Correct electrolytes abnormalities to baseline prior to commencement of refeeding process
- Commence thiamine (at least 100mg IV TDS for the first three days followed by oral 100mg PO daily) before starting and then for first 7-10 days of refeeding
- Commence a multivitamin for first 7 days
- Strict fluid restriction (1.5L) and daily weights
- Consider continuous telemetry
- Protocols on prophylaxis PO electrolyte vary depending on hospital protocol
- Yu ASL, Stubbs JR. Uptodate [Internet]. 2021. Hypophosphatemia: Evaluation and treatment; [cited 2021 Aug 26]. Available from: https://www.uptodate.com/contents/hypophosphatemia-evaluation-and-treatment
- Mount DB. Uptodate [Internet]. 2021. Clinical manifestations and treatment of hypokalemia in adults; [cited 2021 Aug 27]. Available from: https://www.uptodate.com/contents/clinical-manifestations-and-treatment-of-hypokalemia-in-adults
- Yu ASL. Uptodate [Internet]. 2021. Hypomagnesemia: Evaluation and treatment; [cited 2021 Aug 26]. Available from: https://www.uptodate.com/contents/hypomagnesemia-evaluation-and-treatment
- Mehler P, Stubbs JR. Uptodate [Internet]. 2021. Anorexia nervosa in adults and adolescents: The refeeding syndrome; [cited 2021 Aug 29]. Available from: https://www.uptodate.com/contents/anorexia-nervosa-in-adults-and-adolescents-the-refeeding-syndrome
- eTG complete [Internet]. Melbourne (Vic): Therapeutic Guidelines Ltd; 2016. Nutritional support [cited 2021 Aug 30]. Available from; https://tgldcdp-tg-org-au.ezproxy-f.deakin.edu.au/viewTopic?topicfile=nutrition-support&guidelineName=Gastrointestinal#toc_d1e103
Reviewing Consultant/Senior Registrar
Dr James Gaston
Dr Sara Mgaieth