Severe convulsant hypomagnesaemia and short bowel syndrome

Hypomagnesaemia as a primary cause of a generalized seizure is uncommon. A 60-year-old woman with Crohn's disease, who had had recent small bowel surgery and a total colectomy 10 years previously, was admitted complaining of severe nausea, vomiting, fatigue and thirst. Despite oral magnesium therapy she had a generalized seizure due to severe hypomagnesaemia of 0.09 mmol/l (normal range 0.65 to 1.05 mmol/l). Her serum calcium was 1.91 mmol/l (2.03 to 2.63 mmol/l). Hypomagnesaemia can cause generalized convulsions but is usually associated with hypocalcaemia. This patient had an almost normal serum calcium level, and therefore hypomagnesaemia would seem to have been the direct cause of her seizure. Long-term intravenous magnesium was necessary to prevent further seizures.