Abstract: FR-PO0611
A Labor of Love with a Salty Twist: Oxytocin-Induced Severe Hyponatremia
Session Information
- Fluid, Electrolyte, and Acid-Base Disorders: Clinical - 2
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Fluid, Electrolytes, and Acid-Base Disorders
- 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Authors
- O'Brien, Kathryn, UPMC, Pittsburgh, Pennsylvania, United States
- Marszalek, Joan C, UPMC, Pittsburgh, Pennsylvania, United States
- Rondon Berrios, Helbert, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
Introduction
Hyponatremia is the most common electrolyte abnormality in hospitalized patients with a range of etiologies. In pregnancy, unique considerations include a physiologic reset osmostat, hypovolemia from hyperemesis gravidarum, and syndrome of inappropriate antidiuresis in the setting of labor or preeclampsia. We present a case of severe maternal and neonatal hyponatremia associated with oxytocin infusion during labor induction for preeclampsia.
Case Description
A 35-year-old G1P0 woman at 34 weeks' gestation with preeclampsia with severe features and unknown baseline serum sodium (SNa) underwent induction of labor with oxytocin. The next morning, SNa was 120 mmol/L, dropping to 114 mmol/L over 5 hours. Other laboratory data included urine sodium of 18 mmol/L, urine potassium of 33 mmol/L, and urine osmolality of 480 mOsm/kg.
Oxytocin was stopped and she required cesarean section due to worsening condition. Oxytocin resumed briefly for post-op for uterine bleeding. Treatment included hypertonic saline, proactive desmopressin, and fluid restriction with gradual improvement in SNa to 138 mmol/L by discharge on postpartum day 4.
The newborn's SNa was 114 mmol/L at birth. D10 ¼ NaCl and fluid restriction (60 mL/kg/day) were started. At 10 hours of life, IV fluids changed to D10 ½ NaCl with a SNa rise of 8mmol/L over the next 9 hours. D10 ¼ NaCl fluids were resumed, and fluid restriction was adjusted in parallel with total daily fluid goals. SNa improved gradually to 137 mmol/L by day 4.
Discussion
Due to structural similarities to arginine vasopressin, oxytocin can stimulate kidney V2 receptors, leading to water retention and dilutional hyponatremia. Other factors include stress of labor and fluid intake. Recognition of oxytocin as a critical and reversible cause of hyponatremia in pregnant patients, especially preeclamptic patients undergoing induction of labor, is important, with both maternal and fetal implications due to rapid electrolyte equilibration across the placenta. Our case also highlights that management of adult and pediatric patients may differ, especially in newborn and premature infants, who have a low GFR at birth as well as a lack of full renal tubular concentrating ability, both of which may impact the choice of IV fluid used.