What Are Kidney Stones?

QUESTION: Though I have had several attacks, and have listened to all my
doctor's advice, I guess I have never really understood about my kidney
stones. I know the symptoms, the pain is terrible, but what are they and
where do they come from? Your answer would be much appreciated.
------------------------------------------------------------------------------
ANSWER: You describe the pain accurately; it may be excruciating, and follows
the path of the stone as it descends along the urinary tract. Yet there are
some patients who never go through this torture, but have "silent stones" that
may produce no symptoms at all, yet when x-rays are taken, there they are.
Stones are formed from the minerals that occur in our urine. Normally they
may form minute crystals that are passed out of our bodies along with the
urine flow, but sometimes they clump together, and cling to the tissue lining
the inside of the kidney. There they continue to grow as new crystals are
added, and they harden as time passes. They may develop to any size, from a
grain of sand to almost the size of an orange. A number of substances can
form stones--calcium oxalate, calcium phosphate, uric acid, cystine, or
struvite--and some stones are composed of mixtures of these substances. If
you have had stones once, you are at risk of having them again. They occur
mostly in middle aged people, and in areas where hot weather causes excessive
sweating. If body fluids are diminished, the risk for producing stones is
increased. It is the same with reduced or blocked urinary flow; these
occurrences increase the possibility of stones. Certain genetic disorders as
well as foods rich in oxalate and calcium may cause stone formation in some
individuals. Despite the knowledge of all these factors as possibly
contributing to the manufacture of these nasty pebbles, no one is really sure
why they occur or why some people develop them while others do not.