N.B. Use of magnesium for other indications e.g. eclampsia is outside the scope of this guideline. The reference range for serum magnesium is 0.7-1mmol/L. Serum concentrations should be used in conjunction with presenting signs and symptoms to diagnose hypomagnesaemia (see notes below).
Magnesium levels should be monitored, and the dose adjusted as necessary. See flowchart below.
In patients with renal impairment reduced urinary magnesium excretion puts the patient at risk of hypermagnesaemia. See flowchart below for dosing guidance.
N.B. Doses shown in the flowchart are suggested starting doses. Further advice is available from the Biochemistry Department.
Guideline reviewed: February 2023
Page last updated: March 2023