"I was on my way to work when it happened.  I managed to drive myself to the hospital, thinking I'd just turn myself in to die."  (Anonymous quote from a man after passing a kidney stone.) 

Pity the ancient Egyptians who must have gone through the same experience without the benefit of modern medicine.  Scientists have found evidence of kidney stones in a 7,000-year-old mummy and we can only imagine what it must have been like "BP" (before pain killers). 

Knowing the disorder has plagued mankind throughout the ages is small comfort for today's 5 percent of women and 10 percent of men with kidney stones.  The potential of passing a kidney stone is just one of those life experiences that strikes fear in the hearts of the bravest of us.  There is good news, though. Most people with kidney stones will have no symptoms, and unless stones are discovered by chance, they can live their lives in blissful ignorance. 
 
Kidney stones are one of the most common disorders of the urinary tract. Each year, they result in as many as 600,000 emergency room visits and over a million visits to primary care physicians.  And those numbers have been increasing over the past 20 years, particularly in women.

Here's what happens.  Urine contains substances known to both form stones and to prevent them.  Usually, these substances balance each other. When they don't, crystals can form and then bond together. As the surface area of a clump increases, even more minerals are attracted.  When enough crystals clump together, they form a stone.
Kidney stones can be as small as grains of sand or as large as golf balls and range in shape from smooth and round to jagged and spiked.  If a stone stays small enough, it can travel through the urinary tract and pass out of the body in the urine without being noticed.  A large stone that moves into the ureter can cause extreme pain, often described by sufferers as more painful than major surgery, broken bones or even childbirth.

The most common cause of kidney stones is inadequate fluid in the body (dehydration), resulting in concentrated urine.  Other factors that may increase risk include chronic urinary tract infections, some medications and certain genetic and metabolic diseases.