Kidney Stones
Stones Often Cause Severe Pain
Kidney stones can form when a high concentration of chemicals or minerals in the urine separate from the liquid and form small crystals. These substances, usually calcium oxalate, or uric acid, are waste products of the body. Small crystals are often able to pass through the urinary tract without causing symptoms. But when crystals clump together to form larger stones, they can cause severe pain as they try to pass from the kidney through the ureter (the tube that connects the kidney to the bladder). Some types of kidney stones, such as uric acid stones, can be dissolved using a drug taken by mouth, but this treatment doesn’t work with the more common calcium oxalate stones. Depending on the type of stone that is formed, patients prone to stones can help prevent stone formation by drinking plenty of fluids and changing their diet to consume fewer products containing calcium, such as milk and cheese.
The most common cause of kidney stones is the formation of small crystals of minerals or chemicals in the urine. These crystals then clump together to form stones.
Crystals Clump into Stones
Each year, more than one million people in the U.S., mostly men between the ages of 40 and 55, suffer from kidney stones. Kidney stones develop more frequently in people in warm climates, where fluid loss and dehydration are more likely. The most common cause of kidney stones is the formation of small crystals of minerals or chemicals in the urine. Most stones are made of calcium oxalate, and, less frequently, uric acid or cystine. Kidney stones may also form because of an infection in the kidney; antibiotics to fight infection can prevent their formation.
Protective chemicals: In most people, the chemicals in urine keep the crystals from forming. People prone to forming kidney stones may not have enough of these protective chemicals to prevent the stones, especially when other factors that lead to stone formation are present, such as dehydration (from not drinking enough fluids), sedentary life style, or a diet with too much calcium oxalate, uric acid, or vitamin D intake or production. Kidney stones may also appear (infrequently) in patients suffering from metabolic disorders, bowel disease, or kidney disease.
Stone size: Kidney stones, which often have no symptoms, range from the size of a grain of sand to a golf ball. When the diameter of a stone is one-half to one inch or larger, the stone becomes a problem because it cannot pass easily out of the kidney, through the ureter and into the bladder. These larger stones can block the flow of urine in the ureter or bladder, causing a buildup of pressure and spasms in the urinary tract, with irritation of surrounding tissues.
Symptoms: Symptoms of kidney stones include severe pain, described by many patients as the worst pain they have ever felt. The pain starts suddenly in the lower back under the ribs, or in the lower abdomen, and moves forward around the side toward the groin. It may last for a few minutes, or even hours, usually coming in waves. The pain may be accompanied by nausea and vomiting. If the crystals or stones irritate the lining of the urinary tract, there may be blood in the urine. Telltale signs of a urinary tract infection are based on burning while urinating, frequent urge to urinate, fever, chills, and cloudy or bad-smelling urine. Diagnosis is made from a patient medical history, physical examination and an x-ray or ultrasound to detect the location of the kidney stones. To see some stones, a special x-ray (called an intravenous pyelogram [IVP]) uses an injected dye to look at the urinary system. Blood and urine are tested, and if a stone is passed or removed, it may be analyzed by a laboratory to determine what chemicals or minerals are present.
Treatment: In many cases, the treatment of kidney stones requires waiting for the stone to pass by itself, a process that can take hours, days, or weeks. During this time, the patient may take pain medication and should drink enough fluid to produce at least two quarts of urine every 24 hours. The patient should stay physically active, if possible. Although most stones will eventually pass through the urinary tract, in some cases, medical procedures or surgery may be needed to remove the stone. If kidney stones do not pass with time or if they stop urine flow, cause constant bleeding, or growr bigger, a surgical procedure may be used to remove the stone. If the stone is in the ureter, a urethroscope may be passed through the urethra and bladder into the ureter without a surgical incision to remove the stone.
