Severe pre-eclampsia as a rare cause of profound hyponatraemia

Profound hyponatraemia, defined as sodium <125 mmol/L, is a very rare complication of pre-eclampsia (PET) with a relative paucity of cases reported. Pre-eclampsia is a multisystem disorder with a maternal mortality of up to 20%. Hyponatraemia is associated with disease severity, twin pregnancy, advanced maternal age, in vitro fertilisation and HELLP (haemolysis, elevated liver enzymes and low platelets). The authors present the case of a low-risk nulliparous woman presenting with frontal headache and normal BP at 31⁺² weeks gestation. Laboratory investigations confirmed a sodium of 123 mmol/L. Her urine protein creatinine ratio was 322 mg/mmol. She developed PET (BP 171/100 mm Hg) refractory to pharmacological management. She underwent an emergency lower segment caesarean section and was delivered of a live neonate. The maternal serum sodium normalised within 24 hours. Hyponatraemia should be regarded as a marker of severity in the setting of pre-eclampsia and may be an indication for an expedited delivery. Prompt management is required to prevent convulsions, maternal mortality and adverse fetal outcomes.