Kidneys are two bean-shaped organs about the size of the fist. They are located in back of the abdomen on either side of the spine (see Figure 1). Kidneys are part of the complex system, the urinary tract, which removes excess fluid and waste from the blood (see Figure 3). Other structures in this system include the ureters, bladder and urethra. The ureters are two muscular tubes that carry urine from the kidneys to the bladder, a chamber in the abdomen where urine is stored. Urethra is a narrow tube which use for eliminates urine from the body.

Kidney stones are rocks or particles crystal in the urinary tract formed by substances in urine. They vary in size from a grain of sand to the size of a tennis ball. Stones are formed in several different shapes (see Figure 2). Regardless of the size, they are one of the most painful medical problems known. Kidney stones can cause permanent damage to the kidneys if not treated appropriately.

The exact causes of kidney stone formation are not completely known; however, medical researchers believe that stones are the result of mineral supersaturating and crystallization in the urine. In this theory, dehydration causes calcium phosphates, oxalates, urea, uric acids, citrates, complex proteins or other trace elements in urine to combine and crystallize. The primary known causes are:

• Dehydration and lack of sufficient fluid ingestion
• Foreign bodies in the urinary tract
• Diet with excess oxalates, calcium, and vitamin abnormalities
• Urinary infections
• Metabolic diseases (e.g. gout, intestinal)
• Use of certain medication

Normally, urine contains chemicals that prevent crystals from forming. However, some people seem to be more prone to kidney stones than others. If a person is prone to kidney stones, there are several factors which contribute to their formation:

• Recurrent urinary tract infections
• Drinking too little fluid
• Blockage of the urinary tract
• Limited activity for several weeks or more
• Consuming too much calcium oxalate or uric acid in the diet

If a stone stays inside one of the kidneys, it usually doesn't cause a problem unless it becomes so large it blocks the flow of urine. This can cause pressure and pain, along with the risk of severe kidney damage, bleeding and infection. Smaller stones may block the thin tubes that connect each kidney to the bladder or the outlet from the bladder itself. These stones may cause ongoing urinary tract infection or kidney damage. A typical stone attack is a sudden pain occurring at night or in the early morning. The pain starts in the loin and radiates around the abdomen down into the groin. Often, the suspected person cannot sit or lie still. Kidney stone are often confused with other diseases such as acute, colitis, and other bowel disorders.

In many cases we can prevent kidney stones by increasing the amount of liquid we drink and making a few changes in our diet. If these measures are not effective and blood and urine tests reveal we are currently forming stones or the stones we have are getting bigger, the doctor may prescribe certain medications.