Q&A: Why do kidney stones form?

Q: What are kidney stones, and how are they treated?

A: Kidney stones are hard collections of salt and minerals often made up of calcium or uric acid. They affect approximately 11% of men and 6% of women. The stones form in the kidney and then can travel to other parts of the urinary tract. Stones vary in size and in degree of severity.

Calcium oxalate stones make up 70% to 80% of all kidney stones. Calcium-based stones can be influenced by diet, fluid intake, and other factors. Uric acid stones, a less common form, can occur when the urine is acidic. Struvite stones are associated with urinary tract infections.

Kidney stones can cause extreme discomfort. As the stone begins to move through narrower sections of the urinary tract, it typically creates a blockage, causing a build up of pressure in the kidney. This pressure and the associated stretching of the kidney cause symptoms that can include intense pain in the back, side, stomach, groin or genital area. Nausea and vomiting, blood in the urine, or painful urination are also common symptoms.

The cause of a kidney stone can be related to a few different factors. For some people, kidney stones are formed based on diet or low fluid intake. For example, calcium oxalate stones may be related to high intake of oxalate-rich foods like tea, nuts, and leafy green vegetables, among others. Some people may be genetically predisposed to stone formation. Stones are more common in young and middle-aged individuals. Those who have previously developed a stone have a 50% chance of forming another one within 10 years.

CT scan is the best way to diagnose a kidney stone. The scan can show the physician the location and size of the stone and help determine the best form of treatment. Ultrasound and x-rays can also be used.

Recommended treatment for kidney stones is dependent on the type, size and location of the stone. Simple treatment options include pain medication and increased fluid intake to help pass the kidney stone. Another option is extracorporeal shock wave Llithotripsy (ESWL), which uses shock waves that pass through your body to break up the stones. Ureteroscopy, a surgical option, involves passing a very thin telescope through the urinary tract to locate the stone for removal or to break it into smaller pieces. Another option is percutaneous nephrostolithotomy (PCNL), in which a telescope is placed through a puncture in the back into the kidney and the stone can be broken up and removed. It is rare to make a large skin incision to remove the stone.

I encourage patients who suffer from kidney stones to drink at least two liters of water a day if able and to seek medical attention if they develop severe pain, nausea or a fever.

Jeffery David Reich is a urologist with MidLantic Urology in Huntingdon Valley, Pa.