Doctors do not always know what causes a stone to form. While certain foods may promote stone formation in people who are susceptible, scientists do not believe that eating any specific food causes stones to form in people who are not susceptible.

A person with a family history of kidney stones may be more likely to develop stones. Urinary tract infections, kidney disorders such as cystic kidney diseases, and metabolic disorders such as hyperparathyroidism are also linked to stone formation.

Dehydration, alone, is unlikely to cause stones to form and there is always some other factor such as kidney disease, infection, or somebody disturbance that alters the amount or type of substances dissolved in the urine.

Other possible causes are gout and excessive intake of vitamin D or calcium.

• Stones may cause no symptoms, but if a stone becomes stuck or in a urethra (one of a pair of tubes carrying urine from the kidney to the bladder), the muscle of the urethra tries to move the stone down the urethra. Although the urethra is a small tube the pain caused by the muscle trying to move the stone is excruciating. The pain is described as 'colicky'. This means that the pain builds to a crescendo then fades for a short time then returns. This is reckoned to be one of the worst pains anyone can experience. The person cannot sit still and writhes around in agony trying to find a comfortable position.
• The pain may spread to the lower abdomen and into the groin (referred pain).
• Blood in the urine is a common sign of kidney stones. Sometimes the patient may not see this, but a dipstick check of urine will reveal lots blood.
• The closer the stone to the bladder the more likely the person is to feel the symptom of wanting to urinate more frequently.
  

If you've had more than one kidney stone, you are likely to form another; so prevention is very important. To prevent stones from forming, your doctor must determine their cause. He or she will order laboratory tests, including urine and blood tests. Your doctor will also ask about your medical history, occupation, and eating habits. If a stone has been removed, or if you've passed a stone and saved it, the laboratory should analyze it because its composition helps in planning treatment. Many of the stones contain calcium oxalate.

Seek a doctors advice immediately if you suspect that you have kidney stones.

http://www.nlm.nih.gov/medlineplus/kidneystones.html