Kidney stones are solid, rock-like materials that form from the mineral substances contained in the urine. Most kidney stones consist of calcium combined with either oxalate or phosphate. Less common types of kidney stones include a struvite, or infection, stone and the uric acid stone. Even more rare are kidney stones that are made up of cystine. Evidence shows that cystine-based stones tend to run in families.
Kidney stones can grow to a size that can be life threatening or require surgery to remove.
Some large kidney stones cannot be surgically removed due to the age of the patient and the danger of the associated trauma to a vital organ. The size of kidney stones can vary widely from the size of a grain of sand to a golf ball, however most kidney stones are quite small. These types of symptoms require a doctor's help. Such pain can be an indication of movement of the stone or a serious urinary tract blockage requiring immediate medical intervention. Frequently, kidney stone episodes include urinary tract infections.