Most people who’ve had kidney stones can tell you how painful they are. These solid masses—predominantly composed of calcium—form in the kidney and can be excruciating as they pass out of the urinary tract.

“Stones become symptomatic when they cause bleeding or obstruct the flow of urine, usually in the ureter—the organ that connects the kidney to the bladder—which causes pain,” says Dr. Angela Alt, a urologist on staff at St. Luke’s Hospital. “If stones are not causing those issues, they are asymptomatic. Treatment is usually sought for pain or blood in urine (hematuria), but stones are not painful unless they are obstructing the urinary flow.” Nausea and vomiting may accompany the other symptoms, and anyone experiencing this symptom array should see a doctor promptly.

Kidney stones form when substances such as calcium, oxalate, cystine or uric acid occur in very high concentrations in the urine or when the urine volume is very low, explains Dr. Graeme Mindel, a nephrologist (kidney specialist) with Nephrology Associates of St. Louis. “When the urine becomes super-saturated with these chemicals, they form crystals, which become anchored in the kidney; and over time, grow in size to form kidney stones.”

Diabetes, gout, Crohn’s disease, obesity, family history and use of certain medications may predispose people to kidney stones. In addition, diets high in salt, animal protein and spinach may contribute to stone formation.

“Depending on their size and location, stones are treated in different ways. If they are not causing symptoms, they can be observed,” Alt says. Asymptomatic, small kidney stones may pass spontaneously, and those that cause pain but have no other symptoms may only require over-the-counter pain medications.

If the kidney stones do not pass on their own or are large and causing severe symptoms, a variety of treatment options exists. “Shockwave lithotripsy uses a high-energy shockwave to break up the stone and is useful for stones larger than 1 centimeter in size in the kidney or upper ureters,” Mindel says. Other treatments involve a small incision in the skin and insertion of a very thin endoscope into the kidney to remove very large, hard or complex stones, or another type of endoscope that is passed through the urethra and bladder into the ureter and kidney. “The urologist can directly visualize the stone and remove it with a basket-type device or break it up into smaller pieces, which can then be passed more easily,” he says.

Kidney stones can recur—and prevention strategies are formulated based on an evaluation of the original stone, a study of urine chemistries and blood work. Typical strategies to reduce recurrence include increasing fluid intake, limiting sodium, dietary changes (such as reducing animal protein consumption), and medication.

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