5th April 2024

Management

The extent of hypermagnesaemia and presence of comorbidities such as renal failure determines whether treatment is required. A person with normal renal function and good urine output who has received intravenous magnesium for eclampsia will be able to correct the resultant hypermagnesaemia without further treatment. In contrast, a patient with significant renal impairment impacting renal excretion of magnesium, who received a magnesium containing enema, will be at risk of problematic hypermagnesaemia and require treatment.  

For mild hypermagneseamia (2.0 – 4.0 mmol/L) or in asymptomatic patients the source of magnesium should be identified and removed; good urine output maintained and serum concentrations checked after 24 hours. 

Treatment is indicated with senior support and intensive care team involvement where serum magnesium concentrations are > 4.0 mmol/L or if there are significant features of hypermagnesaemia:

• Calcium salts, such as 10 ml of 10% calcium gluconate, administered as a slow intravenous injection over five minutes, are used to antagonise the neuromuscular and cardiovascular side effects of magnesium. Administration may be repeated in arrhythmias. 
• Continuous cardiac monitoring 
• Regular monitoring of serum magnesium levels