Mucocele of the appendix. Two case reports.

UNLABELLED: This study evaluated the independent relationship between the serum uric acid-to-creatinine ratio (UA/Cr) and sarcopenia phenotypes under the latest AWGS 2025 criteria, alongside the moderating role of physical activity (PA). Data were analyzed from 3,685 participants (aged ≥ 50 years) in the 2015 China Health and Retirement Longitudinal Study (CHARLS). Firth's logistic regression and linear models assessed associations between UA/Cr and muscle phenotypes, while diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis. In the fully adjusted model, UA/Cr was significantly associated with increased sarcopenia risk (OR = 1.122, 95% CI: 1.014-1.240, P = 0.025) and reduced muscle strength (β = -0.220, P = 0.009). Notably, after adjusting for BMI, a significant negative correlation emerged between UA/Cr and skeletal muscle mass index (β = -0.003, P = 0.020). Quartile analysis revealed a threshold effect, with risk concentrated in the highest quartile (UA/Cr > 7.25). Furthermore, PA significantly moderated the UA/Cr-muscle mass association (P = 0.048); the negative impact of metabolic load was more pronounced in participants with higher PA levels. Incorporating UA/Cr significantly improved the diagnostic area under the curve (AUC) for sarcopenia in men (+ 0.019, P = 0.038). In conclusion, high serum UA/Cr is an independent risk factor for sarcopenia in middle-aged and older Chinese adults. This association is significantly moderated by PA, highlighting UA/Cr as a robust biomarker for clinical screening, particularly in male populations.

SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s13205-026-05003-7.