Frailty is a geriatric syndrome that primarily affects older patients, but also patients with severe illnesses. It is particularly common among oncology patients, but also among patients with gastrointestinal diseases such as liver cirrhosis or pancreatitis. Sarcopenia, a form of frailty, is defined as a loss of muscle quantity, quality and function. Currently, complex methods such as CT or bioimpedance measurement are available. However, simpler techniques such as ultrasound-based measurement could be alternatives, but still require further validation. In addition, serological muscle markers could support and simplify diagnostics. The aim of this project is to be able to estimate the prognosis of patients at an early stage by measuring sarcopenia using ultrasound and biomarkers.