Preoperative bowel preparation complicated by lethal hypermagnesaemia and acute nephropathy

Hypermagnesaemia is an uncommon but serious disorder. An elderly woman presented with severe cardiovascular collapse, neurologic depression and acute nephropathy, following bowel preparation. Urgent laboratory tests revealed serum magnesium level of 7.5 mmol/L (normal = 0.75-1.05 mmol/L). Prompt resuscitation and treatment of the hypermagnesaemia included intravenous calcium chloride as a physiological antagonist, fluid infusion and frusemide to aid renal excretion of magnesium. There are few case reports of patients who survived hypermagnesaemia levels >7 mmol/L. This is a case report of near-fatal hypermagnesaemia which resolved following early diagnosis and treatment. Hypermagnesaemia may be difficult to diagnose because serum magnesium is not checked routinely and many clinicians are unfamiliar with this uncommon condition. It is a diagnosis of exclusion and may not be recognised as a cause of neurologic or cardiorespiratory depression. Hypermagnesaemia should be considered as a possible diagnosis in elderly or high-risk patients presenting with such symptomatology.