STONES, STONES

Kidney stones are hard objects, made up of millions of tiny crystals. Most kidney stones form on the interior surface of the kidney, where urine leaves the kidney tissue and enters the urinary collecting system. Kidney stones can be small, like a tiny pebble or grain of sand, but often are much larger.

The job of the kidneys is to maintain the body's balance of water, minerals and salts. Urine is the product of this filtering process. Under certain conditions, substances normally dissolved in urine such as calcium, oxalate, and phosphate, become too concentrated and can separate out as crystals. A kidney stone develops when these crystals attach to one another, accumulating into a small mass, or stone.






Kidney stones come in a variety of mineral types.

1. Calcium Stones: Most kidney stones are composed of calcium and oxalate. Many people who form calcium containing stones have too much calcium in their urine, a condition known as hypercalciuria. There are several reasons why hypercalciuria may occur. Some people absorb too much calcium from their intestines. Others absorb too much calcium from their bones. Still others have kidneys which do not correctly regulate the amount of calcium they release into the urine. There are some people who form calcium oxalate stones as a result of too much oxalate in the urine, a condition known as hyperoxaluria. In some cases, too much oxalate in the urine is a result of inflammatory bowel disease, such as Crohn's disease or ulcerative colitis, or other times it may be a consequence of prior intestinal surgery. Calcium phosphate stones, another kind of calcium stone, are much less common than calcium oxalate stones. For some people, calcium phosphate stones form as a result of a medical condition known as renal tubular acidosis.

2. Struvite Stones: Some patients form stones that are composed of a mixture of magnesium, ammonium, phosphate, and calcium carbonate, which is known as struvite. These stones form as a result of infection with certain types of bacteria that can produce ammonia. Ammonia acts to raise the pH of urine which makes it alkaline and promotes the formation of struvite.

3. Uric Acid Stones: Uric acid is produced when the body metabolizes protein. When the pH of urine drops below 5.5, urine becomes saturated with uric acid crystals, a condition known as hyperuricosuria. When there is too much uric acid in the urine, stones can form. Uric acid stones are more common in people who consume large amounts of protein, such as that found in red meat or poultry. People with gout can also form uric acid stones.

4. Cystine Stones: Cystine stones are rare, and they form only in persons with an inherited metabolic disorder that causes high levels of cystine in the urine, a condition known as cystinuria.

HOW IS A KIDNEY STONE DIAGNOSED?

Most people are diagnosed with kidney stones after the thunderclap onset of excruciating and unforgettable pain. This severe pain occurs when the kidney stone breaks loose from the place that it formed, the renal papilla, and falls into the urinary collecting system. When this happens, the stone can block the drainage of urine from the kidney, a condition known as renal colic. The pain may begin in the lower back, and may move to the side or the groin. Other symptoms may include blood in the urine (hematuria), frequent or persistent urinary tract infections, urinary urgency or frequency, and nausea or vomiting.

When your urologist evaluates you for a kidney stone, the first step will be a complete history and physical examination. Important information regarding current symptoms, previous stone events, medical illnesses and conditions, medications, dietary history, and family history will all be collected. A physical examination will be performed, to evaluate for signs of a kidney stone, such as pain in the flank, lower abdomen, or groin.

Your urologist will perform a urinalysis, to look for blood or infection in the urine. A blood sample will also be collected so that kidney function and blood counts can be measured.

Even though all of these tests are necessary, a kidney stone can only be definitively diagnosed by a radiologic evaluation. In some cases, an ultrasound or a simple x-ray, called a KUB, will be adequate to detect a stone. If your urologist requires more information, an intravenous pyelogram (IVP) or a CT stonogram may be necessary.

So You Have A Kidney Stone - What Now

This depends on symptoms, where the stone is in the urinary tract and how big it is.

The type of treatment depends on size, composition and position of the stone. It also depends on your Urologists expertise.

For Stones In The Kidney

The types of treatment include:

a. Dissolution - that is dissolving with medication - only applies to uric acid stones.

b. Extracorporeal Shock Wave Lithotripsy - (ESWL) is the most frequently used procedure for the treatment of kidney stones. In ESWL, shock waves that are created outside the body travel through the skin and body tissues until they hit the denser stones. The stones break down into sand-like particles and are easily passed through the urinary tract in the urine.

In most cases, ESWL may be done on an outpatient basis. Recovery time is short, and most people can resume normal activities in a few days.

Complications may occur with ESWL. Most patients have blood in their urine for a few days after treatment. Minor discomfort in the back or abdomen from the shock waves are also common. To reduce the risk of complications, doctors usually tell patients to avoid taking aspirin and other drugs that affect blood clotting for several weeks before treatment.

Another complication may occur if the shattered stone particles cause discomfort as they pass through the urinary tract.

In some cases, the doctor will insert a small tube called a stent through the bladder into the ureter to help the fragments pass. Sometimes the stone is not completely shattered with one treatment, and additional treatments may be needed. SWL is not ideal for stones more than 3 cms.




This is a segment on an episode in QTV11's RX Men last Sept 2007

c. Percutaneous nephrostolithotomy (PCNL) - In this procedure, the surgeon makes a tiny incision in the back and creates a tunnel directly into the kidney. Using an instrument called a nephroscope, the surgeon locates and removes the stone. For large stones, some type of energy probe (kinetic or laser) may be needed to break the stone into small pieces. Generally, patients stay in the hospital for several days and may have a small tube called a nephrostomy tube left in the kidney during the healing process.
One advantage of percutaneous nephrolithotomy over SWL is that the surgeon removes the stone fragments instead of relying on their natural passage from the kidney.

Illustration of percutaneous nephrolithotomy





d. Open Stone Surgery

This option is still very reliable in our setting.An incision is made on your flank to gain access to the location where the stone is found. This procedure is indicated for large stone burden where ESWL is not a good treatment option, if percutaneous nephrostolithotomy instruments are not available or if an anatomic defect is present leading to stone formation.

Below is a video of a pelvolithotomy (open stone surgery) which I performed



Sometimes kidney stones do not cause any symptoms at all. Such painless stones can be discovered when your doctor is looking for other things on x-rays. Sometimes, although a stone does not cause any pain, it can cause other problems such as recurring urinary tract infections or blood in the urine. It is important not to take these symptoms for granted as it can later lead to damage to your kidneys and eventually kidney failure.

(References: Urology at Hopkins and Urology Sydney)