Hypomagnesaemia in critically ill patients


ABSTRACTBackground: Hypomagnesaemia is a common electrolyte abnormality in critically ill patients. A lot of controversy exists regarding the optimum method of measuring magnesium and the influence of hypomagnesaemia on the morbidity and mortality of these patients.Objectives: To study the prevalence of hypomagnesaemia (measured in serum and RBCs) in critically ill patients and its impact on morbidity and mortality. Patients and methods: Sixty five (65) critically ill patients were studied. Their total serum and erythrocyte Mg (representing intracellular Mg) were measured within 24 hours of intensive care unit (ICU) admission. The patients were followed throughout their ICU stay and assessed regarding the severity of their illness using acute physiology and chronic health evaluation II (APACHE II) score, duration of stay in the ICU and mortality rate.Results: Serum hypomagnesaemia was present in 84.6% of patients. Only 36.9% of patients were having low erythrocyte Mg. There was a weak positive correlation between serum and erythrocytes Mg levels. No patient with normal serum Mg died, compared with 22.2% mortality rate in patients with low serum Mg (p=0.000). No significant difference in the mortality rate was noticed between patients with normal and low erythrocyte Mg. Neither low serum nor erythrocyte Mg had been associated with more severe illness or prolonged ICU stay.Conclusion: Hypomagnesaemia (measured as total serum Mg) is associated with excess ICU mortality, irrespective of the severity of the underlying illness. Intracellular Mg (measured as erythrocyte Mg) does not correlate with ICU morbidity and mortality, and its routine measurement may not be indicated.