Serum and erythrocyte magnesium in critically ill patients?

Objectives: To evaluate the prevalence of serum and erythrocyte magnesium (Mg) abnormalities in patients on admission to the intensive care unit (ICU) and to test the hypothesis that low levels of Mg are associated with a higher mortality. Design: Prospective study. Setting: 14-bed ICU in a 1000-bed teaching hospital. Patients. 179 consecutive patients admitted over a 4-month period. Measurements: Total serum Mg (Mgs) and erythrocyte Mg (Mge) were determined on admission by atomic absorption spectrophotometry. Severity of illness was assessed by Acute Physiology and Chronic Health Evaluation (APACHE) II and the number of organ system failures (OSF) during the first 24 h. The patients were followed up until discharge from hospital. Main results: On admission, 79 patients (44%) were hypomagnesemic and 10 (6%) were hypermagnesemic. A low level of Mge was observed in 119 patients (66%). In patients with similar APACHE II scores and OSF numbers, more of those with hyperMgs died during their ICU stay. However, the Mge value on admission did not correlate with patient outcome. Conclusions: We confirm the high prevalence of Mgs abnormalities as well as Mg deficiency on admission to a medical ICU. Low levels of Mgs and Mge are not associated with higher fatality. HyperMgs was associated with patient death.