Kidney Stones

What is a kidney stone?

Kidney stones are one of the most common disorders of the urinary tract -- an estimated 10 percent of Americans will have a kidney stone in their lifetime. A kidney stone is a hard mass developed from crystals that separate from the urine and build up on the inner surfaces of the kidney. Stones can develop in the kidney, the ureter or the bladder.

There are several different types of kidney stones, and each type contains various combinations of chemicals. The most common type of kidney stones are calcium stones, which contain calcium combined with either oxalate or phosphate. Another type of stone, called a struvite, is caused by infection in the urinary tract. Uric acid stones and cystine stones are the least common types.

What causes kidney stones?

Kidney stones are most commonly caused by not drinking enough water. They can also be caused by various diseases and disorders, and are more likely to develop in people with a family history of kidney stones. Urinary tract infections, kidney disorders and metabolic disorders such as hyperparathyroidism can lead to stone formation. Also, people with rare hereditary diseases, including renal tubular acidosis, cystinuria and hyperoxaluria, can develop kidney stones.

Other causes of stone formation include hyperuricosuria, gout, excess intake of vitamins C or D and blockage of the urinary tract. Some diuretics and antacids could cause stones by increasing the amount of calcium in the urine.

How do I know if I have a kidney stone?

The first symptom of a kidney stone is generally sharp, cramping pain in the back and side in the area of the kidney or in the lower abdomen. The pain begins when a stone moves in the urinary tract, causing blockage and irritation. Nausea and vomiting may occur, and the pain may spread to the groin and genital areas. As a stone grows larger or moves through the urinary tract, blood may appear in the urine and you may feel the need to urinate more often or experience a burning sensation while urinating. Other symptoms include fever, loss of appetite, profuse sweating and diarrhea or constipation.

How are kidney stones treated and prevented?

Most kidney stones will pass through the urinary tract with plenty of water to help move them along. In fact, about 80 percent of stones pass within two days. However, in some cases, medication or other treatment may be necessary to treat kidney stones and prevent development of future stones. About half the people who develop kidney stones will have more stones in the future, so prevention is important.

A doctor may prescribe certain medications to treat and prevent kidney stones. Medications that can prevent calcium stones include thiazieds, potassium citrate, orthophosphate, cellulose phosphate and urease inhibitors. Medications that prevent the formation of uric acid stones are potassium citrate, sodium bicarbonate and allopurinol. Cystine stones may be prevented with penicillamine or tiopronin.

Other treatments to break up stones may be necessary if a stone causes complete block of urine flow, extreme pain that is not controlled with medication, or if it causes a urinary tract infection. These treatment options include extracorporeal shockwave lithotripsy (ESWL), percutaneous nephrolithotomy and ureteroscopy. ESWL uses sound waves that travel through the skin and body tissues until they hit the stones and break them down into particles that can easily pass through the urinary tract. Percutaneous nephrolithotomy may be used if a stone is very large or in a location that is not conducive to using ESWL. In this procedure, a needle is passed through the skin into the kidney to break up or remove the kidney stone. Ureteroscopy uses a tube called a ureteroscope that is passed through the urethra and bladder into the ureter, where the stone is then broken up and removed.

Surgery is a rare option for removing kidney stones and is generally used only when all other options have failed. During surgery, the abdomen and kidney are cut open, the stone is removed and the incisions are closed. Surgery usually requires a six- to nine-day hospital stay.