The UK Medicines Information group have provided excellent guidance on how to replace magnesium.
Useful advice on treatment:
Clinical features
- Usually asymptomatic
- Irritability & lethargy
- Nausea/vomiting
- Psychiatric: confusion, depression, psychosis
- Neuromuscular: Tremors, cramps, tetany, weakness & seizures
- ECG: prolonged PR, ST depression, altered T waves, arrhythmias
Causes
- Dietary such as refeeding syndrome
- GI losses (D&V, high stoma output)
- PPIs
- Alcoholism
- Hypercalcaemia
- Endocrinopathies (aldosteronism, SIADH, DKA)
- Renal losses
- Post-parathyroidectomy
Investigations
- Ensure you’ve checked the other electrolytes (U&Es, calcium)
- Urinary magnesium can help
Management
- See the information above however typically deficiency is replaced orally as per trust guidelines
- IV replacement is another option with 8-16 mmol in 100-200ml of 0.9% sodium chloride or 5% dextrose. However again use the information above & local policies.
- Be careful of causing diarrhoea & rapid accumulation in poor renal function
References & Further Reading
- Hamilton, R.J., 2018. Tarascon adult emergency pocketbook. Jones & Bartlett Learning.
- Katzel, J.A., Vucuscu, R., Garcia, R., 2013. Wards 101 pocket clinician’s survival guide. Börm Bruckmeier Publishing.
- Lewis III, J. L., 2018. Hypomagnesemia. MSD Manual Professional Version.
- OUH Local Guidelines – http://nssg.oxford-haematology.org.uk/oxford/clinical-care/H-95-guidelines-for-management-of-hypomagnesaemia-in-adult-clinical-haematology.pdf.
By Dr Shoaib Hussain
