< previous page page_38 next page >

Page 38
What is a Kidney Stone?
A kidney stone develops from precipitated crystals that separate out from urine and build up on the inner surfaces of the kidney. Normally, urine contains substances that prevent or inhibit the crystals from forming. These are secreted by both the kidneys and the mucous membranes, in one of our body's many exquisitely balanced metabolic acts. These inhibitors do not seem to work for everyone. If the crystals remain small enough and do not clump or bind together, they will travel through the urinary tract and out of the body in urine without even being noticed.
Kidney stones can be formed from a variety of compounds; however, the most common type of stone contains calcium in combination with either oxalate or phosphate. These compounds are part of a person's normal diet and are important components in a variety of tissues, such as bones and muscles.
A less common type of stone is caused by infection in the urinary tract with bacteria that are capable of breaking down urea, a normal urine constituent. This type of stone is called a struvite or infection stone, and may sometimes form extensive ''staghorn'' concretions in the pelvis of one or both kidneys. Much less common are uric acid stones and the rare cystine stone.
Urolithiasis is the medical term used to describe stones occurring in the urinary tract. Other frequently used terms are urinary tract stone disease and nephrolithiasis. Doctors also use terms that describe the location of the stone in the urinary tract. For example, a ureteral stone (or ureterolithiasis) is a kidney stone found in the ureter. To keep things simple, I am using the term "kidney stones."

 
< previous page page_38 next page >

If you like this book, buy it!