Preeclampsia and low sodium: A retrospective cohort analysis and literature review

The aim of this study was to retrospectively analyze the prevalence of severe preeclampsia and low sodium (PALS) among the pregnant population admitted at the University Hospital of Udine in the past 4 years and to compare these data with the current literature.

Only women with a diagnosis of preeclampsia were included. According to the lowest sodium level measured either 5 days before or 5 days after delivery, patients were divided in two groups: women with hyponatremia (<135 mmol/L; severe <120 mmol/L) and women with normonatremia (>135 mmol/L). Moreover, a search literature was performed.

Of 59 patients with preeclampsia, 20 (34%) had hyponatremia. Only one case (1.6%) of severe maternal hyponatremia (sodium level 117 mmol/L) in the setting of preeclampsia was identified. After literature search, a total of 22 manuscripts including 60 case reports of PALS were identified. The lowest sodium level was 113 mmol/L, at 25 weeks of gestation. In most cases hyponatremia was treated with fluid restriction. In only 5 cases hyponatremia was treated with a saline hypertonic solution. Hyponatremia resolution, when reported, occurred in about 48 h. Sodium level in neonates ranged from 118 and 128 mmol/L.

PALS may occur in about a third of women with severe preeclampsia. Severe maternal hyponatremia should be treated with fluid restriction and with hypertonic saline solution. Moreover neonatologists should be alerted in order to treat the neonate for the best outcome.