A number of factors can cause changes in your urine, including the effects of heredity, diet, drugs, climate, lifestyle factors and certain medical conditions. Each of the four main types of kidney stones has a different cause:
Calcium stones. Roughly four out of five kidney stones are calcium stones. These stones are usually a combination of calcium and oxalate. Oxalate is a compound that occurs naturally in some fruits and vegetables. A number of factors can cause high concentrations of these substances in urine. Excess calcium, for instance, may result from ingesting large amounts of vitamin D, from treatment with thyroid hormones or certain diuretics, and from some cancers and kidney conditions. You may also have high levels of calcium if your parathyroid glands, which regulate calcium metabolism, are overactive (hyperparathyroidism). On the other hand, certain genetic factors, intestinal bypass surgery and a diet high in oxalic acid may cause excess amounts of oxalate in your body.
Struvite stones. Found more often in women than in men, struvite stones are almost always the result of chronic urinary tract infections caused by bacteria that produce specific enzymes. These enzymes increase the amount of ammonia in the urine, which is incorporated in the crystals of struvite stones. These stones are often large, may have a characteristic stag's-horn shape and can seriously damage your kidneys.
Uric acid stones. These stones are formed of uric acid, a byproduct of protein metabolism. You're more likely to develop uric acid stones if you've undergone chemotherapy, you eat a high-protein diet or you have certain genetic factors that predispose you to the condition.
Cystine stones. These stones represent only a small percentage of kidney stones. They form in people with a hereditary disorder that causes the kidneys to excrete excessive amounts of certain amino acids (cystinuria).
These factors may increase your risk of developing kidney stones:
Lack of fluids. If you don't drink enough fluids, especially water, your urine is likely to have higher concentrations of substances that can form stones. That's also why you're more likely to form kidney stones if you live in a hot, dry climate, work in a hot environment, such as a commercial kitchen, or exercise strenuously without replacing lost fluids.
Family or personal history. If someone in your family has kidney stones, you're more likely to develop stones too. And if you've already had one or more kidney stones, you're at increased risk of developing another.
Age, sex and race. Most people who develop kidney stones are between 20 and 70 years of age. Men are more likely to develop kidney stones than are women. In addition, white Americans are at higher risk of kidney stones than are black Americans.
Certain diseases. Rare, inherited diseases such as renal tubular acidosis and cystinuria can increase your risk of kidney stones. So can more common disorders such as gout, chronic urinary tract infections and hyperparathyroidism.
Certain medications. Medications can have variable effects on stone formation. For example, diuretics may increase your risk of developing kidney stones in some situations and decrease it in others. If you're at risk, check with your doctor or pharmacist about any medications you take.
Diet. A diet that's high in protein (meat, chicken and fish) and sodium (salt), and low in whole grains and calcium may increase your risk of some types of kidney stones.
Limited activity. You're more prone to develop kidney stones if you're bedridden or very sedentary for a long period of time. That's because limited activity can cause your bones to release more calcium.
Treatment for kidney stones varies, depending on the type of stone and the cause. You may be able to move a stone through your urinary tract simply by drinking plenty of water — as much as 2 to 3 quarts a day — and by staying physically active.
Stones that can't be treated with more-conservative measures — either because they're too large to pass on their own or because they cause bleeding, kidney damage or ongoing urinary tract infection — may need professional treatment. Procedures include:
Extracorporeal shock wave lithotripsy (ESWL). This is a commonly used procedure for treating kidney stones. It uses shock waves to break the stones into tiny pieces that are then passed in your urine. In some cases, you may be partially submerged in a tub of water during the procedure. In others, you may lie on a soft cushion. You'll generally require sedation or light anesthesia due to moderate pain caused by the shock waves. A loud noise is produced each time a shock wave is generated, and you'll wear earphones to protect your hearing.
Your doctor will likely use X-rays or ultrasound to help determine the position of your stone as well as to monitor the status of the stone during treatment.
Complications that may occur with ESWL include blood in the urine, bruising on the back or abdomen, bleeding around the kidney and other adjacent organs, and discomfort as the stone fragments pass through the urinary tract. In addition, if the stone doesn't shatter completely, you may need a second round of ESWL or ureteroscopic stone removal. After treatment, it may take months for all the stone fragments to pass.
Additionally, a study released in April 2006 showed that people treated with ESWL were more likely to develop high blood pressure and diabetes than people who received more conservative treatment for kidney stones. More study of ESWL will be needed to more clearly define the long-term risks.
Percutaneous nephrolithotomy. When ESWL isn't effective, or the stone is very large, your surgeon may remove your kidney stone through a small incision in your back using an instrument called a nephroscope.
Ureteroscopic stone removal. This procedure may be used to remove a stone lodged in a ureter. The stone is snared with a small instrument (ureteroscope) that's passed into the ureter through your bladder. Ultrasound or laser energy can also be directed through the scope to shatter the stone. These methods work especially well on stones in the lower part of the ureter.
Parathyroid surgery. Some calcium stones are caused by overactive parathyroid glands, which are located on the four corners of your thyroid gland, just below your Adam's apple. When these glands produce too much parathyroid hormone, your body's level of calcium can become too high, resulting in excessive excretion of calcium in your urine. Most often, this is the result of a small benign tumor in one of your four parathyroid glands. A doctor can surgically remove the tumor.
In many cases, you can prevent kidney stones by making a few lifestyle changes. If these measures aren't effective and blood and urine tests reveal a correctable chemical imbalance or that the stones you have are getting bigger, your doctor may prescribe certain medications.
Lifestyle changes
For people with a history of kidney stones, doctors usually recommend passing at least 2.5 quarts of urine a day. To do this, you'll need to drink about 3.5 quarts (14 cups) of fluids every day — and even more if you live in a hot, dry climate. Although most liquids count, water is best.
In addition, if you tend to form calcium stones — a combination of calcium and oxalate — your doctor may recommend restricting foods rich in oxalates. These include rhubarb, star fruit, beets, beet greens, collards, okra, refried beans, spinach, Swiss chard, sweet potatoes, sesame seeds, almonds and soy products. What's more, studies show that an overall diet low in salt and very low in animal protein can greatly reduce your chance of developing kidney stones.
As a general rule, restricting your intake of calcium doesn't seem to lower your risk. In fact, researchers have found that women with the highest calcium intake are less likely to develop kidney stones than are women who consume less calcium. Why? Dietary calcium binds with oxalates in the gastrointestinal tract so that oxalates can't be absorbed from the intestine and excreted by the kidney to form stones.
An exception to this rule occurs when an individual absorbs too much dietary calcium from the intestine. In such a circumstance, restricting calcium intake is useful.
Calcium supplements seem to have the same protective effect as dietary calcium, but only if they're taken with meals. When taken on an empty stomach, the calcium can't bind with the oxalates in food.
Medications
Medications can control the level of acidity or alkalinity in your urine and may be helpful in people who form certain kinds of stones. The type of medication your doctor prescribes will depend on the kind of kidney stones you have:
Calcium stones. To help prevent calcium stones from forming, your doctor may prescribe a thiazide diuretic or a phosphate-containing preparation. If you have calcium stones because of a condition known as renal tubular acidosis, your doctor may suggest taking sodium bicarbonate or potassium bicarbonate.
Uric acid stones. Your doctor may prescribe allopurinol (Zyloprim, Aloprim) to reduce uric acid levels in your blood and urine and a medicine to keep your urine alkaline. In some cases, allopurinol and an alkalinizing agent may dissolve the uric acid stones.
Struvite stones. To prevent struvite stones, the first goal is to keep urine free of bacteria that cause infection. Long-term use of antibiotics in small doses may be useful to achieve this goal.
Cystine stones. Cystine stones are the hardest stones and the most difficult to treat. Your doctor may prescribe certain medications to alkalinize the urine or to bind the cystine in the urine in addition to recommending an extremely high urine output.
2007-08-25 15:10:26
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answer #3
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answered by crimsonshedemon 5
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