Hyponatremia associated with preeclampsia

The objective of our study was to evaluate the prevalence and clinical factors associated with hyponatremia in patients with preeclampsia.

This is a descriptive study of all patients who delivered at our institution from 2013 to 2014. Patients with preeclampsia were identified from electronic medical records. Preeclampsia with and without severe features was defined using the criteria outlined in the American Congress of Obstetricians and Gynecologists Hypertension in Pregnancy guidelines. As sodium levels have been shown to be approximately 5 mEq/L lower in pregnancy, hyponatremia was defined as a sodium level <130 mEq/L.

We identified 332 pregnancies complicated by preeclampsia, including 277 singletons and 55 twins. Hyponatremia was noted in 32 (9.7%) patients. Preeclampsia with severe features was present in the majority of patients with hyponatremia, and hyponatremia was more common in those with preeclampsia with severe features compared to those without (P<0.001). Hyponatremia also occurred more frequently in twins (P=0.001) and in older women (P=0.017). Only one patient without hyponatremia had an eclamptic seizure.

Hyponatremia is not uncommon in preeclampsia, and is even more common in those with preeclampsia with severe features and twin gestations. As women with preeclampsia are at risk for hyponatremia, serum sodium should be monitored, especially in women with preeclampsia with severe features or twin gestations.