# The Significance of Renal Impairment in Children with Eating Disorders

## TL;DR

This study shows that many children with eating disorders have kidney issues, and a new method called pdCr is better at detecting these problems than traditional tests.

## Contribution

The study introduces pdCr as a novel, muscle mass-independent indicator for detecting renal dysfunction in children with eating disorders.

## Key findings

- 89.7% of patients showed a drop in creatinine (pdCr) during rehydration.
- eGFR improved in 86.6% of patients with initially low kidney function.
- pdCr was more sensitive than eGFR in detecting renal impairment.

## Abstract

Background: Eating disorders have previously been associated with renal impairment. Low muscle mass reduces serum creatinine used for the calculation of the estimated glomerular filtration rate (eGFR), leading to overestimation of renal function. To solve this problem, the development of a tool to detect renal impairment in individual patients with a specific muscle mass is required to individualize risk assessment for further management. The objectives of our study were as follows: To investigate the percentage drop in creatinine (pdCr) during rehydration as a new indicator of renal dysfunction not dependent on muscle mass and to investigate a correlation between cardiovascular function and fluid management with renal function. Methods: In a 5-year retrospective cohort study of all consecutive children admitted because of an eating disorder, renal function expressed as eGFR on admission and as pdCr between admission and the lowest creatinine level was analysed in relation to cardiovascular parameters and fluid management. Results: We included 29 patients. The mean age was 13.4 years. A pdCr after admission was noted in 26/29 (89.7%). The eGFR was <90 in 15 (65%) and improved to >90 in 13/15 (86.6%). In patients with a fluid management plan, there was a median of 18.6% for those with pdCr and 6.4% (p = 0.02) for those without. Renal dysfunction was not related to cardiovascular parameters. Conclusions: The majority of patients with an eating disorder had renal impairment. PdCr was more sensitive in the detection of renal impairment in individual patients compared to eGFR.