Ionized Blood Magnesium in Sick Children: An Overlooked Electrolyte.

Introduction: Magnesium is a less frequently monitored electrolyte in critically ill patients. Hypomagnesemia is associated with increased need for mechanical ventilation, mortality and prolonged ICU stay. The present study was undertaken to identify the proportion of children with abnormal magnesium levels and correlate it with disease outcome.

Methods: This observational study included children aged 1 month to 12 years hospitalized at the emergency room. Heparinized blood was collected for determination of ionized magnesium, ionized calcium, sodium, potassium and lactate using Stat Profile Prime Plus (Nova Biomedical, Waltham, MA, USA). Clinical outcomes for duration of hospitalization, and death or discharge were recorded.

Results: A total of 154 (102 males) children with median (IQR) age of 11 (4, 49.75) months were enrolled. Sixty one (39.6%) had ionized magnesium levels below 0.42 mmol/l, 63 (40.9%) had normal levels and 30 (19.4%) had hypermagnesemia (>0.59 mmol/l). Hypomagnesemia was associated with hypocalcemia (p < 0.001), hyponatremia (p < 0.001) and hypokalemia (p < 0.02). A higher proportion of children with hypermagnesemia required ventilation than hypomagnesemia (26% vs. 9%) and succumbed (35% vs. 20%), respectively; p > 0.05. Ninety-three (60.3%) had hypocalcemia and 10 (6.5%) children had hypercalcemia. There was good correlation between ionized calcium and magnesium values (r = 0.72, p < 0.001).

Conclusion: Both hypomagnesemia and hypermagnesemia were seen in critically ill children. Patients with hypomagnesemia had significantly higher proportion of other electrolyte abnormalities.