Introduction: Syndrome of inappropriate anti-diuretic hormone (SIADH) is the one of the most common causes of hyponatraemia encountered in hospitalised patients. However, there are very few reported cases of SIADH in pregnancy. This case describes such an entity.
Case Report: A 21 year old lady who was seven weeks pregnant presented to hospital following episode of new onset seizure. She was involved in a road traffic accident seven months prior with associated brain injury. Her blood test revealed new hyponatraemia. Clinically, she was euvolaemic. Biochemistry confirmed a picture of SIADH. Levetiracetam and fluid restriction of one litre a day was commenced. She responded well to fluid restriction with her sodium improving gradually and was discharged with regular follow up at Joint Endocrine/Obstetric Antenatal clinic. Her sodium was maintained in the normative range with 11.25 l daily fluid restriction except on the odd occasions when she did not keep to strict fluid restriction but her sodium did not drop lower than 130 mmol/l. Induction of labour was performed at 37 weeks gestation due raised dopplers and small for gestational age foetus. Her sodium dropped to 125 mmol/l on admission. To ensure strict and accurate fluid restriction, she was commenced on one litre intravenous fluid 24 hourly and kept nil orally. This improved her sodium and she delivered a small but healthy baby girl with weight on the third centile. She remained seizure free throughout. Four months post-partum, with fluid restriction, her sodium remains normal.
Discussion: Fluid requirement in normal pregnancy is around 300 ml/day higher than non-pregnant women. This provides a challenge in managing SIADH in the context of pregnancy. Very little guidance is available in managing these patients. Our experience has shown that fluid restriction to around one litre daily in pregnancy for SIADH seemed safe.