Transactions of the 70th annual meeting of the pacific coast obstetrical and gynecological society
Symptomatic hypocalcemia after tocolytic therapy with magnesium sulfate and nifedipine☆,☆☆

https://doi.org/10.1016/j.ajog.2004.02.050Get rights and content

Abstract

Objectives

In this study, we presented 2 cases and evaluated the evidence for symptomatic hypocalcemia after treatment with magnesium sulfate alone or combined with use of nifedipine.

Study design

Case reports, such as the one that follows, and literature review were used. A 25-year-old gravida presented at 33 weeks' gestation with advanced preterm labor. She received magnesium sulfate followed by nifedipine and experienced bilateral hand contractures 12 hours after discontinuation of magnesium sulfate. Total serum calcium was 5.4 mg/dL. A 35-year-old gravida presented at 26 weeks' gestation with ruptured membranes and received magnesium sulfate until it was discontinued prematurely because of pulmonary edema. Twenty hours later she experienced bilateral hand contractures; total serum calcium was 5.9 m/dL. Symptoms for both patients resolved with calcium gluconate therapy.

Results

Hypocalcemia is a well-recognized complication of magnesium sulfate infusion. These are the fifth and sixth symptomatic case reports, as identified by Medline Search. Our first case is the only report in which the subsequent use of nifedipine may have been a factor. Little has been reported on the possible toxicity associated with the combined or sequential use of magnesium sulfate and nifedipine.

Conclusion

Marked hypocalcemia is clearly associated with magnesium sulfate infusion, is likely dose related, and may appear after discontinuation of magnesium sulfate therapy. Moreover, while the evidence for synergistic toxicity of magnesium sulfate and nifedipine is sparse, caution is advised when these agents are used together.

Section snippets

Case 1

A 25-year-old Hispanic female, gravida 2, para 1, presented with preterm labor at 33 weeks' 4 days' gestation. Her past medical history and prenatal care were unremarkable. She consumed 2 to 3 glasses of milk per day during her pregnancy, with other calcium supplementation unknown. She was transported from a community hospital to our tertiary care hospital after receiving a 6-g loading dose of magnesium sulfate, then 3 g/hr maintenance. The magnesium sulfate was incrementally decreased to 1.5

Case 2

A 35-year-old East Indian female, gravida 1, para 0, presented with preterm premature rupture of membranes (PPROM) and uterine contractions at 25 weeks' 6 days' gestation. Prenatal care issues included vaginal bleeding at 17 weeks and uterine fibroids; past medical history was otherwise unremarkable. She reported drinking 2 glasses of milk per day during pregnancy, and taking roughly 5 tablets (500 mg each) of calcium carbonate per week as needed for heartburn. Upon presentation, the patient

Literature review

Professional medical librarians conducted Medline literature searches for articles in English published between 1966 and 2002, first for nifedipine or magnesium sulfate and hypocalcemia, second for nifedipine and magnesium sulfate and drug interactions. A third search for articles on hypocalcemia and pregnancy, and a fourth search for magnesium sulfate review articles were limited to the years 1990 to 2002. The references in these review articles were checked for case reports possibly missed by

Comment

These are only the fifth and sixth case reports of symptomatic hypocalcemia associated with magnesium sulfate therapy in the English literature that we could find by Medline search. They are only the third and fourth associated with the use of magnesium sulfate for tocolysis, and unlike the two previous cases, our patients became symptomatic after the magnesium sulfate was discontinued. Nifedipine alone does not appear to cause hypocalcemia. However, our first case raises the possibility that

References (18)

There are more references available in the full text version of this article.

Cited by (0)

☆

Presented at the Seventieth Annual Meeting of the Pacific Coast Obstetrical and Gynecological Society, September 16-21, 2003, Anchorage, Alaska.

☆☆

Reprints will not be available from the authors.

View full text
Copyright © 2004 Elsevier Inc. All rights reserved.