PURPOSE

Among complications of malnutrition secondary to anorexia nervosa (AN) or atypical anorexia nervosa (AAN), renal impairment remains poorly elucidated. Evaluating renal function in hospitalized pediatric patients with AN and AAN undergoing refeeding will yield important information to guide clinicians in screening and managing renal dysfunction in this population.

METHODS

This is a secondary analysis of data from the Study of Refeeding to Optimize Inpatient Gains trial, a multicenter randomized clinical trial comparing higher calorie refeeding versus lower calorie refeeding in 120 adolescents and young adults hospitalized with medical instability secondary to AN or AAN. Baseline disease characteristics were obtained. Vital sign measurements, weight, electrolytes, and fluid status were evaluated daily to ascertain medical stability. Renal function on admission and throughout hospitalization was quantified using daily creatinine measurement and calculation of the estimated glomerular filtration rate (eGFR) using the modified Schwartz equation. Regression analysis and mixed linear models were utilized to evaluate factors associated with eGFR.

RESULTS

Of the 111 participants who completed treatment protocol, 33% had a baseline eGFR less than 90, suggesting renal impairment. Patients who experienced more rapid weight loss and more severe bradycardia were more likely to have low admission eGFR. While eGFR improved during refeeding, eGFR change by day based on refeeding treatment assignment did not reach statistical significance (95% confidence interval, -1.61, 0.15]; p = .095).

DISCUSSION

Renal impairment is evident on admission in a significant number of adolescents and young adults hospitalized with AN and AAN. We demonstrate that short-term medical refeeding yields improvement in renal function.