Predictors of hypophosphatemia during refeeding of patients with severe anorexia nervosa.

Objective: Hypophosphatemia of refeeding is one of the most dangerous complications seen during the treatment of patients with anorexia nervosa. Although easily detectable and treatable, hypophosphatemia is under-recognized as a complication of refeeding. Specific risk factors for the development of hypophosphatemia are likely to exist among patients with severe anorexia nervosa. The purpose of this study was to identify clinically useful markers that may predict the development of or protection from hypophosphatemia during refeeding.

Methods: We conducted a retrospective case-control study of 123 patients with severe anorexia nervosa admitted for medical stabilization at the ACUTE Center for Eating Disorders between October 1, 2008 and December 31, 2013. Risk factors for refeeding hypophosphatemia were determined by multivariate logistic regression from clinical parameters and laboratory values measured at the time of admission.

Results: The prevalence of hypophosphatemia was 33.3% (41 of 123 patients). Higher hemoglobin was the only risk factor associated with a higher odds of developing hypophosphatemia (adjusted odds ratio [aOR], 1.56 [95% confidence interval [CI], 1.12-2.18]). Statistically significant protective factors against the development of hypophosphatemia were observed with higher body mass index (aOR, 0.54 [95% CI, 0.39-0.75]), higher serum potassium (aOR, 0.29 [95% CI, 0.14-0.62]), and higher serum prealbumin (aOR, 0.91 [95% CI, 0.84-0.99]).

Discussion: Four independent factors associated with refeeding hypophosphatemia were identified. Identification of findings which correlate with hypophosphatemia, or the lack thereof, has the potential to facilitate appropriate triage of patients with anorexia nervosa for closer monitoring during refeeding.