Understanding Kidney Stones

By Craig Rinder, MD

Kidney stones are one of the most common problems seen by urologists. It is estimated that 10 to 15 percent of Americans have kidney stones. There are various causes for kidney stones as well as many different types. Most kidney stones contain calcium but some may be composed of other substances such as uric acid.

Many people first suspect they have a kidney stone because they feel pain in their lower back, abdomen or side, depending on where it’s located in either the kidney or ureter. But some stones will not cause any pain at all. Other symptoms that may indicate a kidney stone include nausea and vomiting, chills and sweats, blood in the urine or a sudden urge to urinate. Any one of these symptoms is worth talking about with your primary healthcare provider, who will refer you to a urologist if they suspect a kidney stone.

Computerized Axial Tomography (CAT or CT scan) is the best tool for detecting a kidney stone. The stone appears as a very bright white spot on the CT image. Ultrasounds or x-rays may also be used in conjunction with CT or instead of it. But a CT scan will show upwards of 98 percent of kidney stones and will almost always identify the stone if one is present.

You cannot tell from looking at a CT if the stone is going to grow. But you can tell exactly where it is and what effect it’s having. A kidney stone’s location often has more to do with the pain and discomfort a patient feels than its size. It’s believed that the pain is normally caused by obstruction of urine flow. So depending on where they are, small stones can be very painful and large stones can be painless.

A stone that isn’t causing pain or obstruction can be left alone and monitored. If it doesn’t get bigger or doesn’t hurt then we don’t really need to do anything about it. While many of these stones will pass on their own without any medical intervention, we can prescribe pain medication to help people get through the hard parts.

If the stone does not pass on its own and is causing pain that cannot be controlled or if it is causing an infection or illness, surgical treatment is often recommended. Almost all kidney stones are treated with minimally invasive techniques. It’s very unusual nowadays that a patient requires a surgical incision and open procedure to remove kidney stones.

The most commonly performed procedure for kidney stones is called extracorporeal shock wave lithotripsy, or just ESWL. This involves placing a device next to the patient’s body in the vicinity of the stone, which generates shockwaves with enough energy to break the stone into pieces, often no bigger than grains of dust. These will pass out of the kidney or ureter and the stone will be gone.

Some stones are located in places that can’t be easily targeted by a lithotripter. For these we have a procedure called ureteroscopy, which involves passing a scope into the bladder and up through the ureter to where the stone is located. The stone would then be removed either intact or fragmented with a laser. For larger stones, we might instead make a tiny incision in the patient’s back and pass a scope through the incision to fragment and remove it with a laser or lithotripter.

There’s a 50 percent chance that a person who has had one kidney stone will get another one within five years. A urologist would continue to monitor patients and offer preventive measures to keep stones from recurring.

The two most important measures for preventing kidney stones are eliminating excess weight and drinking enough water to make about two liters of urine each day. We know that people with a high body-mass index, which measures obesity, have a higher risk of getting another stone. We also know that keeping the urine dilute will help prevent formation of a stone.

Depending on the chemical compound of the crystals forming the stone, a change in diet might help prevent more stones from forming. Reducing the amount of sodium or animal proteins, including seafood, in a person’s diet might help. In some cases, reducing consumption of foods like spinach or kale from a diet might be necessary for prevention of kidney stones.

It’s no coincidence that a lot of the things that prevent kidney stones from recurring are also keys to living a healthy life. There are other causes for kidney stones besides an unhealthy diet and lack of exercise, however, including family history, medical history, and the use of some medications and supplements.

If you have kidney stones, your urologist can help you identify possible causes for your stones and recommend strategies for preventing them in the future.

Craig Rinder, MD, is a board-certified urologist and Director of the Men’s Health program at Brattleboro Memorial Hospital. He can be reached at 802-251-8720.