MO606: Indoxyl Sulfate is Predictor for Sarcopenia but Myostatin is Indicator For Muscle Mass in Patients with Chronic Kidney Disease: Analysis From Recovery Study

Abstract BACKGROUND AND AIMS Serum myostatin and indoxyl sulfate (IS) levels are increased according to renal function decline and are the main mediators of chronic kidney disease (CKD)-related sarcopenia. However, a recent report showed that myostatin levels were increased in balance-trained CKD patients associated with increased lean mass. The aim of this study was to assess the association between serum myostatin, IS levels and sarcopenia in CKD patients. METHOD Baseline data from the RECOVERY study (clinicaltrials.gov: NCT03788252) conducted from November 2018 to June 2020 were analyzed in 150 CKD patients (mean CKD-EPI eGFR: 33.8 ± 12.5). A Six-meter gait speed test and handgrip strength (HGS) were assessed. Skeletal muscle index (SMI) was measured by using an InBody S10 based on bioelectrical impedance analysis. Sarcopenia was assessed using the Asian Working Group for Sarcopenia 2019. Serum myostatin levels were assessed by an enzyme-linked immunosorbent assay and serum total IS levels were measured using a high-performance liquid chromatography fluorescence detector. RESULTS The proportion of patients with sarcopenia was higher (12.0% versus 4.1%, P = 0.075) in patients with high IS levels (≥0.365 mg/dL) but was lower (4.2% versus 11.8%, P = 0.087) in patients with high myostatin levels (≥4.5 ng/mL). SMI and HGS were significantly lower in patients with high IS levels but were significantly higher in patients with high myostatin levels. IS levels showed a negative correlation with eGFR, SMI and HGS but myostatin levels showed a positive correlation with SMI, and HGS and no correlation with eGFR. However, the myostatin/SMI ratio reflected muscle mass was negatively associated with eGFR and was not associated with SMI and HGS. Sarcopenia was independently associated with age and IS levels after adjustment for gender, diabetes mellitus, creatinine and myostatin/SMI. CONCLUSION Serum total IS levels are an important predictor for sarcopenia, but serum myostatin levels indicate muscle mass in CKD patients with lower eGFR. Further studies are needed to find new markers related to muscle mass and myostatin such as the myostatin/SMI ratio in CKD patients with lower eGFR.