Irisin: A Promising Diagnostic Biomarker at the Interface Between Systemic Inflammation and Skeletal Muscle Dysfunction in Haemodialysis Patients

Haemodialysis patients (HD) exhibit a pro‐inflammatory condition associated with catabolic and functional muscle disorders whose diagnosis and therapeutic management require more robust biomarkers. Thus, irisin relevance as a predictor of inflammation severity and muscle dysfunction in HD patients was investigated. From a prospective clinical study, irisin, tumour necrosis factor (TNF), C‐reactive protein (CRP), general metabolic markers, body composition, appendicular and respiratory muscle strength were measured at 1‐, 6‐, and 12‐month follow‐up. Body composition, haemoglobin, haematocrit, urea, creatinine, cholesterol, triglycerides, calcium, phosphorus, total protein and albumin levels remain stable in all time‐points investigated. TNF and CRP levels were upregulated, while irisin levels, handgrip strength (HGS), inspiratory (maximal inspiratory pressure—MIP) and expiratory muscle strength (maximal expiratory pressure—MEP) were attenuated in HD patients compared to healthy volunteers. Irisin levels were directly correlated with HGS, MIP, and MEP, partially explaining HGS (40%–54%), MIP (41%–61%) and MEP (40%–56%) variability. Irisin was inversely correlated with CRP and TNF levels, predicting 20%–25% CRP and 59%–63% TNF variability. Irisin exhibited good sensitivity in stratifying HD patients according to inflammatory and muscle strength status. Therefore, our findings indicated that systemic inflammation severity was associated with irisin depletion, which was a temporally stable predictor of muscle strength in HD patients. The discriminatory potential of irisin may be relevant for diagnosing HD patients with marked inflammatory stress and muscle dysfunction, refining the monitoring of CKD and dialysis therapy impact on inflammation and muscle strength, factors linked to functional capacity and risk of death in this population.