High serum concentrations of growth differentiation factor-15 and their association with Crohn's disease and a low skeletal muscle index.

Sarcopenia comprises a low skeletal muscle index (SMI) and low muscle strength (MS) or low physical function. Many sarcopenia biomarkers have been reported. With Crohn's disease (CD), a low SMI is predictive of intestinal complications. Therefore, many CD studies have reported that sarcopenia is defined by SMI alone. This study investigated the sarcopenia frequency by assessing the SMI and MS of Japanese patients with CD and biomarkers predicting a low SMI. We evaluated the SMI using a bioelectrical impedance analysis, handgrip strength, and C-reactive protein, albumin, interleukin-6, tumor necrosis factor-α, growth differentiation factor (GDF)-8, and GDF-15 levels as biomarker candidates for 78 CD patients at our hospital. Sarcopenia and a low SMI were observed in 7.7% and 42.3% of the patients, respectively. There was a significant difference in the GDF-15 levels of the low SMI group and normal group according to the multivariate analysis (P = 0.028; odds ratio [OR], 1.001; 95% confidence interval [CI] 1.000-1.002). When evaluated by sex, males exhibited a negative correlation between the GDF-15 level and SMI (Pearson's r = - 0.414; P = 0.0031), and the multivariate analysis indicated a significant difference in the GDF-15 levels (P = 0.011; OR, 1.001; 95% CI 1.000-1.002). GDF-15 levels may indicate a low SMI with CD.