Circulating Muscle-specific microRNAs and Renal, Nutritional and Inflammatory Biomarkers of Skeletal Muscle Loss During the First 18 Months After Laparoscopic Sleeve Gastrectomy

Metabolic and bariatric surgery produces substantial and durable weight loss, but a considerable proportion of that loss is not adipose tissue. Pooled estimates indicate approximately 8 kg of fat-free mass and 3 kg of skeletal muscle mass are lost within twelve months, with more than half occurring in the first three months. No validated circulating biomarker of skeletal muscle loss exists for this population, and body composition can currently be assessed only intermittently. Muscle-specific microRNAs (myomiRs) are mechanistically plausible candidates but have never been measured in patients undergoing metabolic and bariatric surgery. This study will characterise the trajectory of skeletal muscle loss over eighteen months after laparoscopic sleeve gastrectomy and evaluate, as exploratory analyses, whether circulating myomiRs and routinely accessible renal, nutritional and inflammatory measures track that trajectory.

Inclusion Criteria: * Consecutive adults (≥18 years) * scheduled for primary laparoscopic sleeve gastrectomy * meeting current ASMBS/IFSO indications for metabolic and bariatric surgery Exclusion Criteria: * revisional or secondary bariatric procedure * chronic kidney disease stage 3 or worse * dialysis or transplantation * chronic liver disease with synthetic dysfunction * active or recently treated malignancy * known neuromuscular or myopathic disease * systemic corticosteroid or anabolic agent exposure within three months * cardiac pacemaker or implantable defibrillator * pregnancy or lactation * clinical evidence of abnormal hydration at baseline * inability to perform handgrip or chair-stand testing