2D:4D Digit Ratio and Urinary Stone Disease

This prospective observational case-control study will investigate whether the 2D:4D digit ratio is associated with urinary stone disease. Adults undergoing non-contrast computed tomography at Malatya Training and Research Hospital will be classified as cases if kidney and/or ureteral stones are detected and as controls if no urinary stones are detected and there is no previous history of stone disease or stone surgery. The lengths of the second and fourth fingers of both hands will be measured using a digital caliper by two independent observers who are blinded to the participant group. The study will also examine whether the 2D:4D ratio is associated with recurrent stone disease, stone burden, and bilateral or multiple stones.

Inclusion Criteria: * Age 18 years or older * Provision of written informed consent * Undergoing non-contrast computed tomography at Malatya Training and Research Hospital during the study period * For cases: presence of at least one kidney and/or ureteral stone on non-contrast computed tomography * For controls: absence of stones in the kidneys, ureters, and bladder on non-contrast computed tomography * For controls: no previous physician-diagnosed urinary stone disease or history of stone-related surgery * Feasibility of bilateral second- and fourth-digit length measurements Exclusion Criteria: * Congenital deformity of the hands or fingers * History of hand or finger trauma, fracture, surgery, or amputation that may affect digit length measurement * Severe hand deformity, contracture, or advanced joint disease preventing reliable measurement * Incomplete, inadequate, or technically unreliable 2D:4D measurements * Missing essential clinical, demographic, or imaging data * Pregnancy * Presence of bladder stones * Urinary diversion, major urinary tract reconstruction, or a significant structural urinary tract anomaly