Obstet Gynecol Sci.  2018 Jan;61(1):56-62. 10.5468/ogs.2018.61.1.56.

Total and ionized serum magnesium and calcium levels during magnesium sulfate administration for preterm labor

• Kim WH
• Kim YH
• An Y
• Moon JH
• Noh EJ
• Kim JW

• KMID: 2420152
• DOI: http://doi.org/10.5468/ogs.2018.61.1.56

Abstract

OBJECTIVE
This study aimed to estimate the association between total and ionized magnesium, and the changes in serum magnesium and calcium levels in patients with preterm labor during magnesium sulfate (MgSO4) administration.
METHODS
The study population included 64 women who were candidates for intravenous MgSO4 treatment for preterm labor. Serial blood samples were taken and measured total magnesium (T-Mg), ionized magnesium (I-Mg), total calcium (T-Ca), and ionized calcium (I-Ca) levels every one-week interval (1st, 2nd, 3rd).
RESULTS
There was no significant difference in T-Mg and I-Mg levels during MgSO4 administration (P>0.05). There was no significant difference in T-Ca and I-Ca levels during MgSO4 administration (P>0.05). Compared before and after administration of MgSO4, T-Mg and I-Mg levels and T-Ca levels were changed allow statistically significant (P < 0.05). But, there was no significant difference in the I-Ca serum levels before and after MgSO4 administration (P=0.495). The I-Mg levels for patients with adverse effect were higher than other group but did not reach statistical significance (P>0.05). There was significant correlation between levels of I-Mg and T-Mg (I-Mg=0.395×T-Mg+0.144, P < 0.01).
CONCLUSION
There were no significant differences in serum Mg and Ca levels during MgSO4 administration for preterm labor. Compared to the before and after administration of MgSO4, only I-Ca levels were not substantially changed. There are significant correlations between I-Mg and T-Mg levels during administration of MgSO4 and I-Mg level seemed to have more correlation with adverse effect than T-Mg.

Keyword

Magnesium sulfate; Magnesium; Calcium; Obstetric labor, premature

MeSH Terms

Calcium*
Female
Humans
Magnesium Sulfate*
Magnesium*
Obstetric Labor, Premature*
Pregnancy
Calcium
Magnesium
Magnesium Sulfate

Figure

• 

  Fig. 1 Comparison of total magnesium (T-Mg) and total calcium (T-Ca) levels (A) and ionized magnesium (I-Mg) and ionized calcium (I-Ca) levels (B) in patients with preterm labor between before and after magnesium sulfate administration. Superscript marks considered statistically significant: a)P<0.05 or b)P>0.05.

• 

  Fig. 2 Correlation between ionized and total magnesium (T-Mg) during administration of MgSO4 in patients with preterm labor (n=64). Regression analysis obtained the following equation: Ionized magnesium (I-Mg)=0.395×T-Mg+0.144; F=302.621; P<0.01.

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