What is a kidney stone?
A kidney stone is a solid piece of material that forms from crystallization
of excreted substances in the urine. The stone may remain in the kidney
or break loose and travel down the urinary tract. A small stone may pass
all of the way out of the body, but a larger stone can get stuck in a
ureter, the bladder, or the urethra. This may block the flow of urine
and cause great pain.
Causes & Prevention
Kidney stones are a common problem, affecting about 12 percent of men and
5 percent of women. Stones are typically caused by an imbalance in the
urinary system: too little water, too much oxalate, or too much calcium.