R. SCOTT OWENS
Company: Urology of Central Pennsylvania
Years in Field: 17
Q: What is a kidney stone?
A: A crystalline structure that forms in the kidney from mineral salts that are present in the urine.
Much like a high school chemistry experiment, crystals develop when there’s an excess amount that precipitates out of solution and grows over time. They vary in size from 1 to 2 millimeters up to 30 to 40 millimeters. There are five major types of kidney stones: calcium oxalate, the most common; calcium phosphate; uric acid, seen in gout patients; struvite, which develop from chronic urinary infections; and cystine, an inherited type.
Q: What causes kidney stones?
A: Kidney stones occur in 10 percent of the U.S. population with the geographical Southeast having the highest incidence. Hot, arid climates and reduced water consumption are the most common risk factors. Other causes include increased salt intake; increased consumption of calcium and oxalate rich foods, such as rhubarb, spinach and nuts; high protein diets; and sedentary jobs.
Specific medical disorders that lead to stone formation include: gout; hyperparathyroidism, an excess hormone secretion that results in high calcium levels; and low urinary citrate. Citrate is a natural inhibitor of stone formation.
Q: When do kidney stones require medical treatment?
A: Kidney stones require immediate treatment when they cause obstruction of the urinary tract. This is commonly seen when the stone migrates from the kidney into the ureter, the tube that drains the kidney to the bladder, resulting in significant pain and sometimes infection. Stones located in the kidney are usually asymptomatic and can be treated electively when they reach a size of 5 millimeters or more.
Q: What treatments are used?
A: For stones in the kidney that are less than 2 centimeters, we generally use ESWL (extracorporeal shock wave lithotripsy) to fragment the stone and allow it to pass. This is a technology that delivers a shock wave from outside the body to the stone.
For larger stones, we employ a more invasive technique in which we percutaneously enter the kidney from the back to fragment and remove the stone.
For stones in the ureter, we either insert a small scope through the bladder, into the ureter and utilize a laser to break the stone, or use the less invasive ESWL.
Q: Can kidney stones be prevented? How?
A: Kidney stones can be prevented using dietary modifications. These measures include: increasing water intake (enough to produce 1,500-2,000 milliliters of urine per day), reducing salt intake, and limiting calcium and oxalate consumption.
For uric acid stone formers, limiting protein rich foods and elevating the urinary ph above 6.5 will prevent their development.
Other medical therapies to reduce stone formation include: thiazide diuretics (to reduce calcium excretion), potassium citrate (increase urinary citrate), and Allopurinol (a drug that blocks uric acid formation).
Interview conducted via e-mail by The Patriot-News staff.