Background: Magnesium deficiency can cause weakness, constipation, seizures and arrhythmias. We frequently observe hypomagnesemia during refeeding in AN.
Objective: To determine the incidence and time of onset of hypomagnesemia during refeeding in anorexia nervosa (AN).
Design: Observational cohort study.
Setting: University teaching hospital in Vancouver, Canada.
Patients: Patients with AN (DSM-IV criteria) admitted for refeeding.
Intervention: All patients were admitted for supervised refeeding by meal support, in conjunction with our standard medical and psychological treatment.
Measurements: Serum magnesium was measured daily for 5 days and then 3 times a week.
Results: Fifty patients were admitted for an average of 24 days. Sixty percent (30/50) had low serum magnesium during their admission. Hypomagnesemia was present on admission in 16% but as late as the third week of refeeding in others.
Conclusion: Serum magnesium should be measured on admission and rechecked weekly for the first 3 weeks of refeeding as a minimum.