Severe hyponatremia associated with pre-eclampsia

Pre-eclampsia associated hyponatraemia is a very rare condition that can potentially lead to serious maternal and fetal complications and that constitute a diagnostic and therapeutic challenge even for an experienced physician.

A 25-year old female presented to the clinic at 25.3 weeks of gestation with mild physical signs of edema along with hypertension, proteinuria, and a severe hyponatremia (113 mEq/L). Hyponatremia was classified as hypervolemic and resolved 72 hours after the delivery with water restriction.

The pathogenesis of pre-eclampsia associated hyponatremia is relatively unknown. A non-osmotic stimulation of vasopresin release in the setting of a hypervolemic state with low effective circulating plasma volume is thought to be the main mechanism. Advanced maternal age and nephrotic range proteinuria have been postulated as risk factors, but their causal role remains unclear. Fluid restriction is a reasonable treatment, and maternal outcomes are favourable. This condition is a rare indication for urgent delivery, but neonatal outcomes are variable.