Serum irisin is upregulated in patients affected by amyotrophic lateral sclerosis and correlates with functional and metabolic status

Introduction The progression of amyotrophic lateral sclerosis (ALS) leads to a decline of the nutritional status that represents an independent prognostic factor for survival. Recent studies recognize the muscle tissue as an endocrine organ able to release several molecules, called myokines. Among them, irisin seems to be involved in the regulation of metabolism, body weight and development and function of the nervous system. Objectives (1) To evaluate irisin serum levels in patients with ALS, with comparison to healthy subjects; (2) to assess the possible association of circulating irisin levels of ALS patients with the metabolic status, clinical and biochemical features. Methods We performed an observational, cross-sectional study in 50 ALS patients and 32 age- and sex-comparable healthy controls. Patients underwent to a complete set of neurological, pulmonary and nutritional evaluations. Serum irisin concentration was measured by enzyme immunoassay. According to indirect calorimetry, ALS patients were divided into a normo-metabolic patient group ( n = 24) and a hyper-metabolic patient group ( n = 26). Results ALS patients showed significantly higher serum irisin levels compared to healthy subjects (51.0 ± 37.8 vs 13.1 ± 2.2 ng/mL, p