Objective : Eating disorders (ED) are chronic, intractable conditions with various physical manifestations. One manifestation that is often noted is renal dysfunction. This study retrospectively examined renal dysfunction in inpatients with ED at our hospital.
Methods : The subjects were 149 patients with ED (77 with anorexia nervosa, binge-purge type〔ANbp〕 ; 38 with anorexia nervosa, restricting type〔ANr〕 ; 26 with bulimia nervosa, purging type〔BNp〕 ; and 8 with an ED not otherwise specified〔EDnos〕who were admitted to our department of Psychosomatic Medicine from April 2010 to November 2013. Subjects consented to participation in this study in writing. Aspects such as the type of ED, age upon admission, body mass index (BMI) upon admission, duration of disease, and biochemistry results were examined using medical records. Statistical techniques were used to examine these aspects by the types of ED.
Results : Examination of the number of patients with chronic kidney disease (CKD) indicated that 38.3% of the total patients (57/149) had CKD. The proportion of patients with CKD by the types of ED was 58.4% (45/77 patients) for ANbp, 18.4% (7/38 patients) for ANr, 19.2% (5/26 patients) for BNp, and 0% (0/8 patients) for EDnos. The median estimated glomerular filtration rate (eGFR) of each type was as follows : ANbp, 54.3 (interquartile range, 39.4 to 74.8) ; ANr, 76.8 (interquartile range, 62.2 to 92.0) ; BNp, 77.7 (interquartile range, 61.7 to 89.8) ; and EDnos, 78.7 (interquartile range, 74.2 to 92.9). Patients with ANbp had a significantly lower eGFR compared to that of patients with ANr, BNp, or EDnos (p≤0.05). In patients with ANbp, a significant correlation was noted between eGFR and BMI and between eGFR and duration of disease (eGFR and BMI : r=0.38, p<0.01, eGFR and duration of disease : r=0.44, p<0.01). In patients with BNp, a significant correlation was noted between eGFR and duration of disease (eGFR and duration of disease : r=−0.60, p<0.05). A Mann-Whitney U test was used to compare patients with different types of ED in terms of the presence or absence of hypokalemia (K<3.5 mEq/
l). Results revealed significant differences in the eGFR between patients with ANbp and those with BNp.
Discussion : Patients with ANbp had a significantly lower eGFR than did patients with other types of ED. In addition, results indicated that low BMI, prolonged duration of disease, and hypokalemia can place patients with ED at risk for CKD.
Conclusion : Renal dysfunction is often found in patients with ED. These patients need treatment to protect their kidney function. Patients with ANbp in particular have a high risk of severe renal dysfunction, so they should receive early assessment and intervention.
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