Skip to main content

Hypocalcemia during magnesium therapy for obstetric ICU admissions

Introduction

Intravenous magnesium sulfate is commonly used in obstetric patients with pre-eclampsia. Following a case of acute symptomatic hypocalcemia we retrospectively examined a cohort of patients to investigate the frequency of hypocalcemia.

Methods

Obstetric patients were identified from the ICU admissions database and divided into two groups - those treated with magnesium (for suspected pre-eclampsia) and those admitted for other obstetric indications (postpartum hemorrhage, infection, etc.). The baseline calcium values were compared, as well as the lowest and discharge values. Albumin and magnesium values were also compared. All comparisons used Student's t test.

Results

Data were collected on 88 parturients admitted over 2 years including 40 (45%) who received magnesium and 48 (55%) who did not. Magnesium-treated women were younger (age: 31 ± 7 vs. 36 ± 5 years, P = 0.02). The baseline calcium concentrations were similar for the two groups (2.2 ± 0.2 vs. 2.2 ± 0.1 mmol/l, P = 0.85). Patients receiving magnesium had significantly higher magnesium concentrations (2.1 ± 0.4 vs. 0.7 ± 0.2 mmol/l, P 0.001), and significantly lower calcium concentrations during therapy (1.6 ± 0.3 vs. 1.9 ± 0.3 mmol/l, P 0.001). At discharge, the calcium levels were closer (magnesium treated 1.9 ± 0.2 vs. untreated 2.1 ± 0.1 mmol/l, P = 0.02). The albumin concentrations did not differ between the two groups (magnesium treated 27 ± 13 vs. nontreated 33 ± 23 g/l, P = 0.134). Normal values: calcium 2.15 to 2.55 mmol/l, magnesium 0.7 to 0.95 mmol/l, albumin 35 to 50 g/l.

Conclusion

Magnesium therapy was associated with hypocalcemia. Potential causative mechanisms include a renal excretion interaction and magnesium-induced suppression of parathyroid hormone secretion. Physicians should be aware of the potential for symptomatic hypocalcemia during magnesium therapy.

Author information

Affiliations

Authors

Corresponding author

Correspondence to PD Levin.

Rights and permissions

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Cite this article

Levin, P., Szalat, A., Vizana, M. et al. Hypocalcemia during magnesium therapy for obstetric ICU admissions. Crit Care 17, P442 (2013). https://doi.org/10.1186/cc12380

Download citation

Keywords

  • Magnesium Sulfate
  • Postpartum Hemorrhage
  • Obstetric Patient
  • Intravenous Magnesium
  • Symptomatic Hypocalcemia