What is a kidney stone?

A kidney stone is a solid piece of material that forms from crystallization of excreted substances in the urine. The stone may remain in the kidney or break loose and travel down the urinary tract. A small stone may pass all of the way out of the body, but a larger stone can get stuck in a ureter, the bladder, or the urethra. This may block the flow of urine and cause great pain.

A kidney stone may be as small as a grain of sand or as large as a pearl, and some are as big as golf balls. Approximately 80 percent of kidney stones are less than 2 centimeters in width. They may be smooth or jagged, and are usually yellow or brown in color.

What are the symptoms of kidney stones?

The following are the most common symptoms of kidney stones. However, each individual may experience symptoms differently. Symptoms may include:

• extreme, sharp pain in the back or side that will not go away
• blood in the urine
• nausea and vomiting
• cloudy or odorous urine
• frequent urination
• a burning feeling when you urinate
• fever and chills

Prompt medical attention for kidney stones is necessary.

What causes a kidney stone?

A kidney stone develops from crystals that separate from urine and build up on the inner surfaces of the kidney. Normally, urine contains chemicals that prevent or inhibit the crystals from forming, however, in some people, stones still become formed. Crystals that remain small enough will travel through the urinary tract and pass out of the body in the urine without even being noticed.

• calcium stones
  Calcium stones are the most common type of stones. Calcium is a normal part of a healthy diet and is used by bones and muscles. Calcium not used by the body goes to the kidneys where it is normally flushed out with the rest of the urine. In some people, however, the calcium that stays behind joins with other waste products to form a stone.

• struvite stones
  Struvite stones are a type of stone that contains the mineral magnesium and the waste product ammonia. It may form after an infection in the urinary system.

• uric acid stones
  Uric acid stones may form when there is too much acid in the urine.

• cystine stones
  Cystine stones consist of cystine, one of the building blocks that make up muscles, nerves, and other parts of the body, can build up in the urine and form a stone. Cystine stones are rare. The disease that causes cystine stones (cystinosis) runs in families.

Who gets kidney stones?

Kidney stones occur more frequently in men than in women, and the most common age of diagnosis in men is between 40 and 70 years old.  For women, the prevalence peaks in their 50s.  Caucasians are more likely to get kidney stones than African Americans.

How are kidney stones related to Crohn’s and ulcerative colitis?

Kidney stones, usually composed of either calcium oxalate or uric acid, are much more common in people with IBD than they are in the general population.   Kidney stones are especially a problem in patients who do not absorb fat  in their small intestine due to symptomatic Crohn’s disease and those who have had multiple surgeries due to Crohn’s disease with removal of bowel.

How are kidney stones diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for kidney stones may include the following:

• CT Scan is a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
• intravenous pyelogram (IVP) - a series of x-rays of the kidney, ureters, and bladder with the injection of a contrast dye into the vein - to detect tumors, abnormalities, kidney stones, or any obstructions, and to assess renal blood flow.
• urinalysis - laboratory examination of urine for various cells and chemicals, such as red blood cells, white blood cells, infection, or excessive protein or amounts for calcium, oxalate and urate, etc.
• blood tests - laboratory examination of the blood to detect substances that might promote stone formation.
• Kidney  (renal) ultrasound - a non-invasive test in which a transducer is passed over the kidney producing sound waves which bounce off of the kidney, transmitting a picture of the organ on a video screen. The test is used to determine the size and shape of the kidney, and to detect a mass, kidney stone, cyst or other obstruction in the kidney.

How are kidney stones treated?

Specific treatment for kidney stones will be determined by your physician based on:

• your age, overall health and medical history
• extent of the disease
• your tolerance for specific medications, procedures or therapies
• expectations for the course of the disease
• your opinion or preference

Some kidney stones pass out of the body without any intervention by a physician. In cases that cause lasting symptoms or other complications, kidney stones may be treated with various techniques, including the following:

• shock waves or extracorporeal shock wave lithotripsy (ESWL) - use of a machine to send shock waves directly to the kidney stone to break a large stone into smaller stones that will pass through the urinary system. There are two types of shock wave machines: with one machine, the patient sits in a tub of water, with the other, the patient lies on a table.

• ureteroscope - a long wire with a camera attached to it is inserted it into the patient's urethra and passed up through the bladder to the ureter where the stone is located. A cage is used to obtain the stone and remove it. Alternatively, a laser fiber may be used to evaporate the stone. This procedure can also be used in the kidney.

• tunnel surgery (Also called percutaneous nephrolithotomy.) - a small cut is made in the patient's back and a narrow tunnel is made through the skin to the stone inside the kidney. The physician can remove the stone through this tunnel.

If you think you have a kidney stone, please contact your doctor.