Creatinine is a valuable biomarker for longevity assessment as it reflects the functionality of the kidneys, an essential organ for overall health and longevity. High levels of creatinine may indicate impaired kidney function, which is a significant risk factor for age-related decline and mortality. Monitoring creatinine levels can provide valuable insights into kidney health and help identify potential areas for intervention to promote longevity. Additionally, changes in creatinine levels over time can offer valuable information about the effectiveness of longevity interventions, making it a critical marker for assessing and improving overall health and lifespan.