Biomarkers of frailty

Numerous biomarkers have been proposed to identify the multisystemic age-related syndrome of frailty. Nevertheless, due to its intricate pathophysiology and the lack of a consensus on a comprehensive and universally accepted definition, identifying a single biomarker or set of biomarkers that definitively characterize frailty, its prognosis, and the response to treatment remains challenging. This review examines the principal laboratory biomarkers associated with pathways closely linked to frailty, such as inflammation, oxidative stress, mitochondrial dysfunction, metabolic and endocrine alterations, among others, plus a summary of imaging biomarkers. Given the multifactorial nature of frailty, it is becoming increasingly imperative to evaluate the role of biomarker sets and the combination of laboratory and imaging biomarkers with the clinical criteria for the diagnosis and prognosis of the different frailty-related outcomes, addressing a crucial need in routine clinical practice.