Dr. Jeffrey Rosenblum, M.D.

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Publications: Philadelphia Inquirer

Innovations Prevent, Treat Painful Kidney Stones
April 28, 2005

By Jeffrey Lee Rosenblum, MD.
Urologic Surgeon

It’s been said that the pain of a kidney stone is worse than the pain associated with childbirth. One out of 10 people in the United States will develop a kidney stone in his or her lifetime. Seven to 10 of every 1,000 hospital admissions are for kidney stone treatment.

Kidney stones are crystalline deposits that form in the kidney. The kidneys filter waste products from the blood and excrete them in the urine. If these waste products do not dissolve completely, crystals or kidney stones may form. The most common stones form when there is a relatively high level of oxalate, calcium or uric acid in the urine. This may be a result of increased dietary consumption or absorption, or production by the body. If dehydration occurs, these substances may not dissolve completely and crystals may occur, forming stones. Urine normally contains chemicals that prevent kidney stones, called inhibitors. These inhibitors are citrate, magnesium and pyrophosphate.

The most common types of kidney stones are composed of calcium, uric acid, struvite and cystine.

Approximately 85 percent of stones are comprised predominantly of calcium corn- pounds. The most common cause is excess calcium in the urine. Low citrate levels, adequate urine output, and high levels of oxalate and uric acid may also cause calcium stones. Calcium stones are most commonly of the calcium oxalate variety. Oxalate crystallizes 40 times faster than calcium. Calcium phosphate stones typically occur In patients with metabolic disorders, including hyperparathyroidism and renal tubular acidosis.

The parathyroid glands are located in the neck behind the thyroid. They control the body’s calcium metabolism. Hyperparathyroidlsm results in the over activity of these glands Increasing the body’s calcium. Renal tubular acidosis is an inherited condition in which the body’s inhibitor citrate is reduced, leading to stone formation. Increased intestinal absorption of calcium and kidney calcium leak may also cause stones.
Uric add stones occur in approximately 10 percent of kidney stone patients. They occur in a predominantly acid environment In the body. A diet high in animal protein may predispose one to this type of stone. Gout, a painful joint condition, may cause uric acid stones by releasing excessive uric acid into the blood, which gets filtered into the urine.

Struvite stones are Infection stones.  In a urinary tract Infection, bacteria release chemicals that promote struvite stone formation.  The struvite stone can grow quite large — even filling an entire kidney, They may assume the shape of a deer’s antlers, hence the name "staghorn" stone.

Cystine stones result from a rare inherited condition. A large amount of cystine, an amino acid protein, is spilled into the urine. Diet plays an important role in kidney stone formation. Tea, chocolate and caramelized drinks are high in oxalate. Cranberries may be good for urinary tract infections but are high in oxalate. High doses of vitamin C result in increased ascorbic acid, which turns into oxalate. Salty foods have a high sodium content and should be limited. The kidney absorbs the sodium and in turn excretes calcium in the urine. Of course, adequate water intake should be maintained to avoid dehydration and dilute the above substances.

In order for a stone to cause pain it must be in a position to obstruct the flow of urine within the urinary tract. It may be lodged within the ureter (the tube connecting the kidney to the bladder) or the kidney itself. The pain can be sharp or dull depending on the stones location and the degree of blockage. The discomfort can radiate from the back or flank to the front. It has been described as colicky or intermittent in nature. Nausea, vomiting urinary frequency and blood in the urine can be seen as well.

Diagnosing a kidney stone includes a medical history, a physical exam, imaging, and urine and blood tests. Perhaps the most sensitive and pervasive imaging test Is the CT (Computerized Tomography) Scan, which uses an x-ray scanner and a computer. Image slices are obtained of the patient’s abdomen and pelvis, without an Intravenous or oral contrast agent, to identify the stones location and size.

Treatment of kidney stones depends on the size, location, duration of symptoms, and presence or absence of urinary tract infection. Stones 4 mm and smaller usually pass without intervention in 90 percent of cases. The patient is instructed to strain his or her urine to attempt to catch the stone. It is then sent for analysis to direct further therapy.

Urologists can perform various procedures to break up or remove stones. Extracorporeal Shock Wave Lithotripsy (ESWL) is a non-invasive method using focused impulses outside of the body. These “shock waves” pulverize stones in the kidney or ureter without any cutting.

Today, stones that in the past had to be treated by open surgery can be treated using ESWL. Some stones may require ureteroscopy — a fiberoptic instrument is passed Into the bladder arid up the ureter. The stone may be removed using basket-type devices or broken up using a laser. Other minimally invasive technologies can be utilized depending on the particular circumstances.

Prevention strategies and medical management are pursued and adjusted according to the clinical situation and stone composition. Various medications can be utilized to prevent or treat kidney stones. Depending upon the type of stone, these medications Include water pills, calcium binding compounds, vitamins and citrate. Even calcium itself has been used to prevent some stones by binding oxalate in the intestine.

For more information about kidney stones and other urologic Issues or to schedule an appointment, contact Jeffrey Rosenbium, M.D. at 610-594-444 or 877-MD-URINE(toll-free), or visit www.rosenblumurology.com.

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