562: Hyponatremia among preeclampsia patients - feature of severity

Abstract

Hyponatremia occurring in the preeclamptic patient was previously described in several case reports and in one cohort study. The significance of this, presumably rare, complication is yet unknown. The aim of our study was to describe its prevalence and the correlation between hyponatremia and other preeclampsia complications. An Electronic Medical Record based retrospective cohort study included all singleton deliveries at Hadassah Medical Center between 2003-2015. Preeclampsia with and without severe features was defined using the criteria outlined in the current ACOG Hypertension in Pregnancy Guidelines. Sodium levels during pregnancy have been shown to be approximately 5 mEq/L lower than in non-pregnancy, therefore, hyponatremia was defined as a sodium level ≤ 130 mEq/L, and severe hyponatremia as < 125 mEq/L. A control group of 79 women admitted to the high risk antepartum unit at our facility for other pregnancy complications. We identified 700 pregnancies complicated by preeclampsia during the study period. Hyponatremia was noted in 102 (14.6%) patients compared with 0 of 79 women in the control group. Hyponatremia was strongly correlated with severe features of preeclampsia: HELLP syndrome, abnormal kidney function, severe hypertension as well as early delivery, low birth weight, unplanned CS, and NICU admission of the newborn (Table 1). Severe hyponatremia was strongly correlated with preeclampsia with severe features. Surprisingly, in a group of preeclamptic patients without severe features, hyponatremia was correlated with several adverse pregnancy outcomes (Table 2). Hyponatremia is not a rare complication of preeclampsia, and is even more common in patients with preeclampsia and severe features. As women with preeclampsia are at risk for hyponatremia, serum sodium should be monitored, especially in those women with severe features. In preeclamptic patients without severe features, hyponatremia may, by it self, be a sign of severity. However, the current study was too small to point toward hyponatremia as a sign of severity and further research is needed.