Kidney Function

Severe hyponatremia is a rare complication of preeclampsia. Of 8 cases reported in the literature, the postulated mechanism was hypervolemic hyponatremia in 5 and syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in the remaining 3. Irrespective of the type, early diagnosis and treatment are of the utmost importance. Hyponatremia in patients with preeclampsia may be associated with increased risk of maternal seizures, and fetal sodium level < 130 mEq/L (<130 mmol/L) can cause fetal jaundice, tachypnea, seizures, and polyhydramnios. Treatment of hyponatremia presents unique challenges in the setting of preeclampsia. Demeclocycline and conivaptan are contraindicated in pregnancy, and furosemide, a US Food and Drug Administration (FDA) class C drug, is best avoided. Fluid restriction alone may not always be effective, and worsening hyponatremia should be an indication for induction of labor. We report the fourth case of SIADH in patients with preeclampsia and discuss the pathophysiologic characteristics and management of severe hyponatremia in preeclampsia.