Serum levels of the adipomyokine irisin in patients with chronic kidney disease.

BACKGROUND: Irisin is an adipomyokine with claimed anti-obesity and anti-diabetic effects. This hormone has been insufficiently studied in patients with advanced chronic kidney disease (CKD).

OBJECTIVE: To perform an exploratory analysis of serum irisin levels in patients undergoing different CKD treatments.

METHOD: Following a cross-sectional design, we estimated serum levels of irisin in 95 patients with CKD managed conservatively (advanced CKD), with peritoneal dialysis (PD) or with haemodialysis, and compared our findings with a control group of 40 healthy individuals. We investigated the correlations between serum irisin and demographic, clinical, body composition and metabolic variables.

RESULTS: Irisin levels were lower in all the CKD groups than in the control group. The univariate analysis revealed limited correlations between irisin, on the one hand, and fat (but not lean) mass, glomerular filtration rate (GFR) and plasma albumin and bicarbonate, on the other. The multivariate analysis confirmed that advanced CKD patients managed conservatively (difference 111.1ng/ml), with PD (25.9ng/ml) or haemodialysis (61.4ng/ml) (all P<.0005) presented lower irisin levels than the control group. Furthermore, PD patients presented higher serum levels of irisin than those on haemodialysis (difference 39.4ng/ml, P=.002) or those managed conservatively (24.4 ng/ml, P=.036). The multivariate analysis also identified plasma bicarbonate (B=3.90 per mM/l, P=.001) and GFR (B=1.89 per ml/minute, P=.003) as independent predictors of irisin levels. Conversely, no adjusted correlation between irisin and body composition markers was found.

CONCLUSIONS: Serum irisin levels are low in patients with CKD and show a consistent correlation with GFR and plasma bicarbonate levels. PD patients present higher levels of irisin than those managed conservatively or with haemodialysis. Our study confirms a general inconsistency of the association between serum irisin levels, on the one hand, and body composition and metabolic markers, on the other.