Risk factors for refeeding hypophosphatemia in Japanese inpatients with anorexia nervosa

Refeeding in patients with anorexia nervosa (AN) is associated with a risk of refeeding syndrome, which is a disruption in metabolism with a variety of features including hypophosphatemia. We evaluated the risk factors for refeeding hypophosphatemia (RH) during nutritional replenishment in Japanese patients with AN.

We retrospectively examined clinical data for 99 female inpatients (mean age 30.9 ± 10.7 years; range, 9 - 56 years).

RH (phosphate < 2.3 mg/dL) occurred within 4.8 ± 3.7 days of hospital admission and was still observed at 28 days after admission in 21 of the 99 cases (21.2%). Oral or intravenous phosphate was given to some patients to treat or prevent RH. Patients with RH had a significantly lower body mass index, were older, and had higher blood urea nitrogen than those without RH. Severe complications associated with RH were recorded in only one patient who showed convulsions and disturbed consciousness at Day 3 when her serum phosphate level was 1.6 mg/dL.

The significant risk factors for RH that we identified were lower body mass index, older age, and higher blood urea nitrogen at admission. No significant difference in total energy intake was seen between the RH and no RH groups, suggesting that RH may not be entirely correlated with energy intake. Precisely predicting and preventing RH is difficult, even in patients with AN who are given phosphate for prophylaxis. Thus, serum phosphate levels should be monitored for more than 5 days after admission.