Kidney stones are one of the most common kidney problems. They are usually caused by a buildup of certain minerals that clump together inside your kidneys. Large kidney stones cause pain when they move through your urinary tract. You may not feel anything if you have a small kidney stone that moves easily through your urinary tract. When a kidney stone moves through your urinary tract and out of your body with your urine, it is called passing a kidney stone. Learn more about the causes, symptoms and treatment of kidney stones.