Association of hypomagnesemia and mortality in acutely ill medical patients.

OBJECTIVE

To test the hypothesis that the mortality rate of acutely ill patients admitted to a medical ward or medical ICU is higher for those patients who present with hypomagnesemia than for those patients who do not present with hypomagnesemia.

DESIGN

Prospective, observational study.

SETTING

Emergency Department admissions to the medical ward and medical ICU of a tertiary care teaching hospital serving an inner city patient population.

SUBJECTS

A total of 381 consecutive acutely ill patients.

MEASUREMENTS

Serum magnesium concentrations and other metabolic variables were measured on admission from the Emergency Department. Acute Physiology and Chronic Health Evaluation (APACHE II) scores were computed for all patients, and mortality rates were determined for hypomagnesemic and normomagnesemic groups.

MAIN RESULTS

Hypomagnesemic and normomagnesemic groups had comparable APACHE II scores and other variables. However, the mortality rates of the hypomagnesemic ward and medical ICU groups were approximately twice (p < .01) the rate of the normomagnesemic groups. Additionally, the duration of hospital survival in those patients who died was approximately 8 days less for hypomagnesemia than normomagnesemia, but not for ward admissions. Other associated metabolic abnormalities were frequently observed in both hypomagnesemic and normomagnesemic groups, including hypokalemia and hypocalcemia.

CONCLUSIONS

Hypomagnesemia detected at the time of admission of acutely ill medical patients is associated with an increased mortality rate for both ward and medical ICU patients.