The main aim of the study is to investigate and compare the possible acute effect of standard PCNL, mini-PCNL and RIRS on renal function. Secondary aims are to investigate the efficacy (stone-free rate), safety (complication rate, long-term kidney function) and other parameters (operation, fluoroscopy and hospitalization time) concerning the 3 endourological operations (PCNL, mini- PCNL, RIRS) for the treatment of renal calculi.