Critical Hypermagnesemia in Preeclamptic Women Under a Magnesium Sulfate Regimen: Incidence and Associated Risk Factors.

Magnesium sulfate is used as prophylaxis and treatment of severe preeclampsia/eclampsia, albeit its safety and toxicity are a concern. We designed this study to estimate the incidence of critical hypermagnesemia in severely preeclamptic women under a magnesium sulfate regimen at 8 h following its administration and to identify the associated risk factors as the primary outcomes. Also, secondary outcomes were to compare baseline characteristics, laboratory findings, and maternal-neonatal complications stratified by the baseline serum magnesium (Mg2+ ) in those women, and to assess the degree of agreement between patellar reflex and serum Mg2+ concentration 8 h following magnesium sulfate administration. We conducted a retrospective study including severely preeclamptic women receiving magnesium sulfate from June 2016 to May 2021. We enrolled 429 women in the study. Two-hundred sixty-one (60.8%) of the included women developed critical hypermagnesemia. Preeclamptic women with high baseline serum Mg2+ concentration demonstrated significantly affected renal functions, hepatic transaminase activities, and low platelet count as well as more reported maternal complications compared to those with low baseline serum Mg2 . Multivariable logistic regression revealed that a lower gestational age, a higher uric acid concentration, and a higher baseline serum Mg2+ concentration were independently associated with an increased risk of critical hypermagnesemia. The agreement between deep tendon reflex assessment and serum Mg2+ concentration was slight although not significant. The maternal-neonatal outcomes were non-significant in women with critical hypermagnesemia. More vigilant monitoring through assessment of both serum Mg2+ concentration and deep tendon reflex should be considered especially in high-risk women.