Kidney stones (renal lithiasis, nephrolithiasis) are small, hard mineral deposits that form inside your kidneys, made of mineral and acid salts.
Kidney stones have many causes and can affect any part of your urinary tract from your kidneys to your bladder.
Often, stones form when the urine becomes concentrated, allowing minerals to crystallize and stick together.
Passing kidney stones can be quite painful, but the stones usually cause no permanent damage.
Depending on your situation, you may need nothing more than to take pain medication and drink lots of water to pass a kidney stone. In other instances surgery may be needed.