Kidney stones occur when salts in the urine form a solid crystal. These stones can block the flow of urine and cause infection, kidney damage or even kidney failure. Between four and eight per cent of the Australian population suffer from kidney stones at any time. The risk of kidney stones is about one in 10 for men and one in 35 for women. Kidney stones can range in size from a grain of sand to a pearl or even larger. They can be smooth or jagged, and are usually yellow or brown. A large stone may get stuck in the urinary system. This can block the flow of urine and cause great pain.
There are four major types of kidney stones:
- Stones formed from calcium not used by the bones and muscles, combined with oxalate or phosphate. These are the most common kidney stones.
- Stones containing magnesium and the waste product ammonia, called struvite stones. These form after urine infections.
- Uric acid stones, formed when there is too much acid in the urine.
- Cystine stones, which are rare and hereditary.