Audit of automated requesting of serum magnesium measurement in patients with hypocalcaemia

Abstract

Laboratory computer records for 71 consecutive hypocalcaemic patients (albumin-adjusted calcium < 2.00 mmol/L) without chronic renal failure revealed that 50 (70%) did not have serum magnesium measured. A second review of computer records was carried out 6 months after the initiation of an automated requesting program. This identified 14 patients with hypomagnesaemia (serum magnesium < 0.70 mmol/L) who may otherwise have been undiagnosed. The direct cost to the laboratory was an additional 19 magnesium analyses per month. It is concluded that hypomagnesaemia is commonly associated with hypocalcaemia but is under-diagnosed. Automated requesting of serum magnesium measurement is a cost-effective way of identifying these patients. However, the fact that only half of these patients had follow-up magnesium requests suggests that there may be a need for further education of clinicians in the significance of hypomagnesaemia.