A kidney stone is a hard, crystalline mineral material formed within the kidney or urinary tract. Kidney stones are a common cause of blood in the urine (hematuria) and often severe pain in the abdomen, flank, or groin. Kidney stones are sometimes called renal calculi.
The condition of having kidney stones is termed nephrolithiasis. Having stones at any location in the urinary tract is referred to as urolithiasis, and the term ureterolithiasis is used to refer to stones located in the ureters.
When should I call a doctor?
Pain in the shaded areas may be caused by a kidney stone.
If you have a kidney stone, you may already know how painful it can be. Most kidney stones pass out of the body without help from a doctor. But sometimes a stone will not pass. It may even get larger. Your doctor can help.
You should call a doctor if you have any of the following signs:
• extreme pain in your back or side that will not go away
• blood in your urine
• fever and chills
• urine that smells bad or looks cloudy
• a burning feeling when you urinate
These may be signs of a kidney stone that needs a doctor's care
A number of different medical conditions can lead to an increased risk for developing kidney stones:
• Gout results in chronically increased amount of uric acid in the blood and urine and can lead to the formation of uric acid stones.
• Hypercalciuria (high calcium in the urine), another inherited condition, causes stones in more than half of cases. In this condition, too much calcium is absorbed from food and excreted into the urine, where it may form calcium phosphate or calcium oxalate stones.
• Other conditions associated with an increased risk of kidney stones include hyperparathyroidism, kidney diseases such as renal tubular acidosis, and other inherited metabolic conditions, including cystinuria and hyperoxaluria.
• Chronic diseases such as diabetes and high blood pressure (hypertension) are also associated with an increased risk of developing kidney stones.
• People with inflammatory bowel disease are also more likely to develop kidney stones.
• Those who have undergone intestinal bypass or ostomy surgery are also at increased risk for kidney stones.
• Some medications also raise the risk of kidney stones. These medications include some diuretics, calcium-containing antacids, and the protease inhibitor indinavir (Crixivan), a drug used to treat HIV infection.
Dietary factors and practices may increase the risk of stone formation in susceptible individuals. In particular, inadequate fluid intake predisposes to dehydration, which is a major risk factor for stone formation. Other dietary practices that may increase an individual's risk of forming kidney stones include a high intake of animal protein, a high-salt diet, excessive sugar consumption, excessive vitamin D supplementation, and possible excessive intake of oxalate-containing foods such as spinach. Interestingly, low levels of dietary calcium intake may alter the calcium-oxalate balance and result in the increased excretion of oxalate and a propensity to form oxalate stones.
What can my doctor do about a problem stone?
If you have a stone that will not pass by itself, your doctor may need to take steps to get rid of it. In the past, the only way to remove a problem stone was through surgery.
Now, doctors have new ways to remove problem stones. The following sections describe a few of these methods.
Your doctor can use a machine to send shock waves directly to the kidney stone. The shock waves break a large stone into small stones that will pass through your urinary system with your urine. The full name for this method is extracorporeal shock wave lithotripsy. Doctors often call it ESWL for short. Lithotripsy is a Greek word that means stone crushing.
Two types of shock wave machines exist. With one machine, you sit in a tub of water. With most newer machines, you lie on a table. A health technician will use ultrasound or x-ray images to direct the sound waves to the stone.
In tunnel surgery, the doctor makes a small cut into the patient's back and makes a narrow tunnel through the skin to the stone inside the kidney. With a special instrument that goes through the tunnel, the doctor can find the stone and remove it. The technical name for this method is percutaneous nephrolithotomy.
A ureteroscope looks like a long wire. The doctor inserts it into the patient's urethra, passes it up through the bladder, and directs it to the ureter where the stone is located. The ureteroscope has a camera that allows the doctor to see the stone. A cage is used to catch the stone and pull it out, or the doctor may destroy it with a device inserted through the ureteroscope.
Ask your doctor which method is right for you.