Incidence of ionized hypomagnesemia in adult patients undergoing noncardiac major surgery: a prospective observational trial.

BACKGROUND

The present study aimed to investigate the incidence of preoperative ionized hypomagnesemia and compare with that of total hypomagnesemia.

METHODS

This prospective observational study included 536 patients aged >20 years who were scheduled for elective surgery. Total and ionized magnesium levels were evaluated before and after the surgery. Based on these levels, patients were classified into the following groups: ionized hypo- (<0.42 mmol/L), normo- (0.42-0.59 mmol/L) and hypermagnesemia (>0.59 mmol/L), as well as total hypo- (<1.9 mg/dL[0.78 mmol/L]), normo- (1.9-2.7 mg/dL[0.78-1.11 mmol/L]) and hypermagnesemia (>2.7 mg/dL [1.11 mmol/L]). The primary objective was to establish the incidence of preoperative ionized hypomagnesemia.

RESULTS

There was a marked difference between the incidence of preoperative ionized and total hypomagnesemia (28% vs. 19%; p<0.001). The postoperative values of ionized magnesium, ionized calcium, and albumin were significantly lower than the respective preoperative values (p<0.001 for all three variables).

CONCLUSION

The incidence of hypomagnesemia, determined by ionized magnesium concentration, was higher than that determined by total magnesium concentration.