Serum Magnesium in the First Week of Life in Extremely Low Birth Weight Infants

Abstract

Background: Evidence that antenatal administration of magnesium sulfate (MgSO₄) to women in preterm labor may confer fetal neuroprotection is growing. MgSO₄ crosses the placenta and can affect the neonate. Magnesium homeostasis in extremely low birth weight (ELBW) infants remains to be clarified. Objectives: We aimed to assess the natural progression of serum magnesium (Mg) in ELBW infants not exposed to antenatal MgSO₄ during the first month of life. Methods: Laboratory data of a group of ELBW infants born in a tertiary center over a 1-year period were analyzed. Serum Mg was recorded daily for the first week and thereafter each week for a month for each infant. Concurrent calcium, phosphate and alkaline phosphatase were measured. Results: 51 preterm infants (24 female) with a birth weight <1,000 g were included (33 were born at <27 weeks’ gestation). The mean magnesium ranged from 0.9 to 1.1 mmol/l over the first week with a minimum of 0.62 mmol/l and maximum of 1.53 mmol/l. Mg rises in the first few days before stabilizing and remains within a narrow range thereafter. Conclusions: In ELBW infants, Mg tends to rise initially then stabilize and remain normal thereafter. The effect of antenatal MgSO₄ on magnesium homeostasis requires further study.

Prenatal Therapy with Magnesium Sulfate and Its Correlation with Neonatal Serum Magnesium Concentration

“…The effect of antenatal MgSO 4 on magnesium homeostasis requires further study. 21,29 In no exposed group, Mg was 1.92 mg/dL AE 0.25 in day 1 and 2.33 mg/dL AE 0.38 in day 2 and in treated group, Mg was 2.68 mg/dL AE 0.52 and 2.60 mg/dL AE 0.35, respectively.…”

“…Mg then stabilizes toward the 66 hours of life in the exposed group and toward the 14 hours in the nonexposed, different from other publications. 21 Other than the dose regimens, factors such as gestational age, birth weight, and maternal serum magnesium levels, may influence the higher fetal serum magnesium. Renal clearance of magnesium in the initial days of life is decreased in neonates and especially in preterm neonates, causing the levels of magnesium to remain high for long periods.…”

“…Magnesium homeostasis in extremely low birth weight infants (ELBW) is not fully understood. 21 The main purpose of this study is to analyze the association between the dose of magnesium administered to the mother and the neonatal serum magnesium concentrations of patients admitted to a tertiary neonatal intensive care unit (NICU) who have received MgSO 4 as a neuroprotective agent.…”

Factors Associated With Changes in Magnesium Levels in Asymptomatic Neonates: A Longitudinal Analysis

“…The reports on changes in magnesium levels after birth have presented mixed findings. For instance, some authors did not find any changes in the levels of magnesium in the first week of life ( 8 ), others have stated that levels rise initially and subsequently stabilize ( 9 ). Furthermore, there is little consensus on addressing hypomagnesemia in neonates.…”

“…While some researchers have used magnesium supplements for hypomagnesemia ( 10 ), others found that low Mg levels became normal even in the absence of treatment ( 11 ). The need for more studies to understand magnesium homeostasis has also been highlighted by researchers ( 9 ).…”