<h4>Objective</h4>To investigate the association between serum cystatin C (CysC) levels and tophus presence, and to assess its diagnostic value for structural joint damage in gout.<h4>Methods</h4>In this cross-sectional study of 598 gout patients, we examined the association between serum CysC and both the presence and burden of tophi. The gene discussed is CST3; the disease is gout.