Our results indicated that rs2607420 CC genotype in the intron region of the ITPKC gene is associated with a lower eGFR by both Modification of Diet in Renal Diseases (P = 0.0405) and Cockcroft-Gault (P = 0.0215) equations in patients with calcium nephrolithiasis. Here, ITPKC is linked to Calcium nephrolithiasis.