Over-the-counter antacids linked to severe hypokalaemia in the context of threatened preterm labour

A healthy multiparous woman presented at 35 weeks and 4 days’ gestation with threatened preterm labour on multiple occasions. An incidental finding of severe hypokalaemia (2.4 mmol/L) was detected on routine blood tests. The cause of this hypokalaemia was not initially obvious. It was eventually linked to overuse of over-the-counter antacids for pregnancy-associated heartburn. The patient was managed with parenteral and then oral electrolyte replacement which corrected a pH of 7.55, bicarbonate of 36.7 mEq/L and a base excess 13.1. In this case report we consider whether hypokalaemia could be linked to uterine irritability and threatened preterm labour, whether antacids were being abused in the context of an eating disorder and the importance of taking a full drug history.