Kidney stones are small, hard mineral deposits that form in the kidney. They may stay in the kidney or travel down the urinary tract. Kidney stones are one of the most common problems of the urinary system. Not all stones are able to pass through the urinary tract on their own. But stones that are smaller, such as those the size of a grain of sand or even a small pearl, can pass.
Stones in the kidney often do not cause any symptoms and can go undiagnosed. When a stone leaves the kidney, it travels to the bladder through the ureter. Sometimes, the stone can become lodged in the ureter. When this happens, the stone blocks the flow of urine out of the kidney and it can cause the kidney to swell, often causing a lot of pain.
A sharp, cramping pain in the back and side, often moving to the lower abdomen or groin may occur with stones. The pain often starts suddenly and comes in waves. It can come and go as the body tries to get rid of the stone. A feeling of an intense need to urinate is also possible with stones.
If you've had a kidney stone and want to avoid another one, drink water throughout the day to stay hydrated. Remember to drink more to replace fluids you've lost when you sweat from exercise or are in hot weather. Try to avoid eating too much food high in oxalates. Common foods high in oxalates include blueberries, chocolate, peanut butter or spinach. You may want to also reduce the amount of animal protein (red meat, pork, etc.) in your diet.
Dr. Timothy D. Averch is professor of urology and director of Endourology at the University of Pittsburgh School of Medicine. He is also director of the UPMC Kidney Stone Center.