Hypomagnesemia in the ICU - Does Correction Matter?

Magnesium is a cation that is constantly being rediscovered. A number of studies have linked low magnesium levels to poor outcome of critically ill patients. Despite this hypomagnesemia continues to be under-recognized and uncorrected. There are no studies, in our knowledge, that have assessed the impact of correction of hypomagnesaemia on the outcome of the ICU patient.

To determine the standard Mg levels in a healthy population sample and to correlate it with western data. To estimate the admission Mg levels in critically ill patients admitted to the ICU and to determine if routine correction of hypomagnesaemia altered their outcomes as compared with the retrospectively collected data of a similar group of patients admitted to the same ICU prior to the routine testing of Mg levels. This was an observational study carried out in the intensive care unit of a tertiary hospital in south India.

The mean serum magnesium in a sample of healthy Indian population was noted to be 2.112 mg/dl, which is consistent with that of the western data. Among the critically ill admitted to the medical ICU, the incidence of Hypomagnesemia (defined as serum Mg+2 of ≤1.7mg/dl on admission), was 23.96%. The study group in whom serum Magnesium was routinely corrected, showed a decrease in the mean total duration of icu stay (94.265 vs. 99.443 hours with p=0.78); the need for mechanical ventilation (52.08% vs. 65.625%) and the duration of Mechanical Ventilation (36.64 vs. 58.75 hours with p=0.04). Mortality was significantly higher in the comparison group (p=0.01) (39.6% vs. 22.9%).

The range of Magnesium levels in a healthy Indian population matches that of the west despite variations in diet and lifestyle. Routine screening and replacement of magnesium in critically ill patients with hypomagnesaemia resulted in reduction of morbidity and statistically significant reduction in overall ICU mortality.