Hypomagnesemia during refeeding in anorexia nervosa.

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.