Irisin and Volume Overload are Associated with Protein Energy Wasting in Peritoneal Dialysis Patients.

BACKGROUND/AIMS: Protein energy wasting (PEW) is a common medical phenomenon that is observed in maintenance dialysis patients. PEW also increases morbidity and mortality of these patients. Its pathogenesis is unclear. We hypothesize that serum irisin levels and volume overload may induce PEW in peritoneal dialysis (PD) patients. The aim of this study is to measure serum irisin levels, evaluate volume status of PD patients, and study their correlations with PEW in PD patients.

METHODS: This study is a cross-sectional study with 160 PD patients from the PD center of Peking University Third Hospital and 35 healthy control subjects. PD patients were divided into PEW group and non-PEW group according to PEW diagnosis criteria. Serum irisin concentrations were measured by ELISA. Volume overload status (volume overload is defined as overhydration value ≥2 liters) of PD patients was analyzed by bioelectrical impedance.

RESULTS: The serum irisin levels were significantly lower in PD patients compared with those of the controls (113.2±11.8 ng/ml vs. 464.2±37.4 ng/ml, P<0.01). The serum irisin levels were lower in PD patients with PEW than those of the patients without PEW (106.5±15.2 ng/ml vs. 117.4±17.6 ng/ml, P<0.01). PEW is more prevalent in patients with volume overload than patients without volume overload (62.5% vs. 43.1%, x2=5.756, P=0.016); however, no direct relationship was found between irisin levels and volume overload status. The independent influencing factors of PEW were serum irisin, serum albumin, and volume overload.

CONCLUSION: Our results are the first to provide clinical evidence of the association between serum irisin, volume overload, and PEW in PD patients. PEW may inhibit the release or synthesis of irisin from skeletal muscles, and volume overload may aggravate PEW in PD patients.