Kidney stone

CEBU, Philippines – 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.

Who's at risk?

Anyone may develop a kidney stone, but people with certain diseases and conditions (see below) or those who are taking certain medications are more susceptible to developing kidney stones. Urinary tract stones are more common in men than in women. Most urinary stones develop in people 20-49 years of age, and those who are prone to multiple attacks of kidney stones usually develop their first stones during the second or third decade of life. People who have already had more than one kidney stone are prone to developing further stones.

People with certain medical conditions are at an increased risk for developing kidney stones. These medical conditions include gout, hypercalciuria (high calcium in the urine), hyperparathyroidism, kidney diseases such as renal tubular acidosis, and other inherited metabolic conditions, including cystinuria and hyperoxaluria.

Chronic diseases such as diabetes and hypertension are also associated with increased risk of developing kidney stones. Likewise, people with inflammatory bowel disease are more likely to develop kidney stones. Those who have undergone intestinal bypass or ostomy surgery are also at increased risk.

Symptoms

People who have kidney stones often report the sudden onset of excruciating, cramping pain in their low back and/or side, groin, or abdomen. Changes in body position do not relieve this pain. The abdominal, groin, and/or back pain typically waxes and wanes in severity, characteristic of colicky pain (the pain is sometimes referred to as renal colic). It may be so severe that it is often accompanied by nausea and vomiting. The pain has been described by many as the worst pain of their lives, even worse than the pain of childbirth or broken bones. Kidney stones also characteristically cause bloody urine. If infection is present in the urinary tract along with the stones, there may be fever and chills. Sometimes, symptoms such as difficulty urinating, urinary urgency, penile pain, or testicular pain may occur due to kidney stones. Some kidney stones, however, may not produce symptoms (known as "silent" stones).

Causes

Among people in industrialized countries, kidney stones are more common than stones in the bladder. The opposite is true for residents of developing countries of the world, where bladder stones are the most common. This difference is believed to be related to dietary factors. In the present, many kidney-stone cases are believed to be related to the obesity epidemic.

A family history of kidney stones is also a risk factor. Kidney stones are more common in Asians and Caucasians. Uric acid kidney stones are more common in people with chronically elevated uric acid levels in their blood (hyperuricemia). A small number of pregnant women develop kidney stones, and there is some evidence that pregnancy-related changes may increase the risk of stone formation. It remains rather unclear whether the physio-physical changes of pregnancy are directly responsible for kidney stone formation or if the women have another underlying factor that predisposes them to kidney stone formation.

Kidney stones form when there is a decrease in urine volume and an excess of stone-forming substances in the urine. The most common type of kidney stone contains calcium in combination with either oxalate or phosphate. A majority of kidney stones are calcium stones. Other chemical compounds that can form stones in the urinary tract include uric acid, magnesium ammonium phosphate (which forms struvite stones), and the amino acid cysteine.

Dehydration from reduced fluid intake or strenuous exercise without adequate fluid replacement increases the risk of kidney stones. Obstruction to the flow of urine can also lead to stone formation. In this regard, climate may be a risk factor for kidney stone development, since residents of hot and dry areas are more likely to become dehydrated and susceptible to stone formation.

Kidney stones can also result from infection in the urinary tract; these are known as struvite or infection stones. Metabolic abnormalities, including inherited disorders of metabolism, can alter the composition of the urine and increase an individual's risk of stone formation.

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.

Diagnosis

The diagnosis of kidney stones is suspected when the typical pattern of symptoms is noted and when other possible causes of the abdominal or flank pain are excluded. Which is the ideal test to diagnose kidney stones is controversial. Imaging tests are usually done to confirm the diagnosis. Many patients who go to the emergency room will have a non-contrast CT scan done. This can be done rapidly and will help rule out other causes for flank or abdominal pain. However, a CT scan exposes patients to significant radiation, and recently, ultrasound in combination with plain abdominal X-rays have been shown to be effective in diagnosing kidney stones.

In pregnant women or those who should avoid radiation exposure, an ultrasound examination may be done to help establish the diagnosis.

Treatment

Most kidney stones eventually pass through the urinary tract on their own within 48 hours, with ample fluid intake. Anti-inflammatory drugs and narcotics may be used for pain control when over-the-counter pain control medications are not effective. Intravenous pain medications can be given when nausea and vomiting are present. Caution must be exercised in taking certain medications - like aspirin - if lithotripsy is to be done because of increased risk of bleeding.

Although there are no proven home remedies to dissolve kidney stones, home treatment may be considered for patients who have a known history of the problem. Since most kidney stones, given time, will pass through the ureter to the bladder on their own, treatment is directed toward control of symptoms. Home care in this case includes the consumption of plenty of fluids. Pain medication may be applied if there is no contraindication to its use.

There are several factors which influence the ability to pass a stone. These include the size of the person, prior stone passage, prostate enlargement, pregnancy, and the size of the stone. A 4 mm stone has an 80 percent chance of passage, while a 5 mm stone has a 20 percent chance. Stones larger than 9 mm rarely pass without specific treatment.

There are drugs prescribed for stones that do not rapidly pass through the urinary tract. For kidney stones that do not pass on their own, a procedure called lithotripsy is often used. In this procedure, shock waves are used to break up a large stone into smaller pieces that can then pass through the urinary system.

Surgical techniques have also been developed to remove kidney stones when other treatment methods are not effective. This may be done through a small incision in the skin (percutaneous nephrolithotomy) or through an instrument known as an ureteroscope passed through the urethra and bladder up into the ureter.

Prevention

Rather than having to undergo treatment, it is best to avoid kidney stones in the first place when possible. It can be especially helpful to drink more water, since low fluid intake and dehydration are major risk factors for kidney stone formation. Also drinking lemon juice or lemonade may be helpful.

(Reference: www.medicinet.com)