It’s the kidney’s job to filter blood and remove extra waste and water, which gets passed as urine. Urine contains many waste chemicals, which can sometimes form crystals that clump together – and these clumps are kidney stones. The stones are hard, rock-like crystals of varying sizes and shapes; anywhere from as small as a grain of sand to a golf ball.
There are four main types of kidney stones:
- Calcium stones combined with oxalate or phosphate are the most common.
- Struvite stones are often horn-shaped and quite large, mostly caused by urine infections.
- Uric acid stones are often softer than other forms of kidney stones.
- Cystine stones are rare and hereditary. They look more like crystals than stones.