BACKGROUND: Although magnesium is important in the biology of blood pressure regulation, little clinical data exist on the association of hypermagnesemia and blood pressure. METHOD:: We examined the association of hypermagnesemia and SBP in a cross-sectional study of 10 521 ICU patients from a single tertiary care medical center, 6% of whom had a serum magnesium above 2.6 mg/dl at time of admission. RESULTS:: In a multivariable analysis, hypermagnesemia was associated with SBP 6.2 mmHg lower [95% confidence interval (CI) -8.2, -4.2, P < 0.001] than in patients with admission values of serum magnesium 2.6 mg/dl or less. Each mg/dl increase in serum magnesium was associated with a decrease in SBP of 4.3 mmHg (95% CI -5.5, -3.1, P < 0.001). In addition, hypermagnesemic patients had a 2.48-fold greater likelihood (95% CI 2.06, 3.00, P < 0.001) of receiving intravenous vasopressors during the first 24h of ICU care, independent of admission SBP. CONCLUSION:: Our findings add support to the biologic importance of magnesium regulation in blood pressure control.National Institute of Biomedical Imaging and Bioengineering (U.S.) (Grant 2R01 EB001659
