Analysis of hypo- and hypermagnesemia in an intensive care unit cohort.

INTRODUCTION: The aim of this study was to evaluate if magnesium deviations correlate with higher 180 day overall mortality or increased morbidity, compared to controls.

METHODS: We conducted a retrospective study on 5369 patients with 22,003 magnesium values treated at the Adult Intensive Care Unit at Skåne University Hospital, Lund, Sweden during 2006-2014. The patients were retrospectively divided into a control group with only normal magnesium values 0.7-1.0 mmol/l, and three study groups; hypomagnesemic; Mg2+ < 0.7 mmol/l, hypermagnesemic; Mg2+ > 1.0 mmol/l and an unstable mixed group showing both hypo/hypermagnesemia. Gender, age, disease severity represented by maximum organ system SOFA score, renal SOFA score, lowest potassium value and diagnoses classes were included in a Cox hazard model in order to adjust for confounding factors, with time to death in the first 180 days from the ICU admission as outcome.

RESULTS: The hypermagnesemic study group and the mixed group showed increased hazard ratios for mortality; 1.4 (CI 98.3% 1.2, 1.6, P < 0.0001) and 2.1 (CI 98.3% 1.2, 2.8, P < 0.0001) respectively, compared to controls, while the hypomagnesemic group did not reach significance. In addition, patients in the hypermagnesemic and the mixed groups are older, more ill with significantly higher EMR and SOFA scores and show significantly longer ventilator times and ICU stays, compared to controls.

CONCLUSIONS: Patients with magnesium deviations are more ill compared to patients with explicitly normal magnesium values throughout the ICU stay. Cox analysis suggests that the magnesium deviation itself might have an impact on mortality.