A kidney stone is like a small rock that forms in the kidney. Kidney stones form as certain chemicals join together to become crystals in the urine, which is produced by the kidneys. In most cases, the crystals are too tiny to be noticed, and pass harmlessly out of the body. However, in some cases, they can build up inside the kidney and become “stones”. Anyone can form a kidney stone, but patients are at higher risk if they are: male, Caucasian, extremely overweight, have had kidney infections in the past, and or have a family member that has had kidney stones. Additional risk factors include: dehydration, a high salt diet, and certain foods, including leafy green vegetables, chocolate, coffee, tea, and nuts. Once a person has developed a stone, they are more likely to develop others in the future.
There are a few different kinds of stones and each has a different cause. These four types are:
Calcium-oxalate: The most common kidney stones. They can be caused by eating too much calcium or vitamin D, some medicines, genetics and other kidney problems.
Struvite: These stones affect women more than men. They can grow very large and may harm the kidneys more than other stones. Having kidney infections often may cause struvite stones.
Uric acid: These stones may be caused by eating too much animal protein or by genetics.
Cystine: These stones are very rare. They are caused by cystinuria, a genetic kidney disease.