An unusual cause of hypocalcaemia: magnesium induced inhibition of parathyroid hormone secretion in a patient with subarachnoid haemorrhage.

We describe a case of a woman with subarachnoid haemorrhage who developed hypocalcaemia and decreased serum parathyroid hormone levels due to hypermagnesemia. The patient had been receiving bisphosphonate therapy prior to admission and this may have contributed to the severity of the problem.