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Kidney Stones: Why Something So Small Causes So Much Pain

Two kidney stones in a macro shot

The National Kidney Foundation says they send a half-million people to emergency rooms each year because of kidney stones - hard objects made from chemicals in the urine. They’re very small, but at a couple of centimeters or more, kidney stones can be quite painful. Dr. R. Carrington Mason, a urologist with Methodist Health System, explains what causes the pain.

Highlights from Dr. Mason’s interview:

What causes the pain: The stone is blocking the drainage tube, and pressure is building up behind it as the kidney continues to make urine. And in doing so, the kidney is distended or the drainage tube of the kidney is distended and that’s what causes the pain experience.

Treatment of a kidney stone: The majority of kidney stones can be treated conservatively by pushing fluids, pain medicines to handle the colic episodes. More recently, we use a medicine called tamsulosin, which is a men’s prostate medicine that dilates the distal ureter (drainage tube) and can facilitate passage of the stones.  Once they get above – depending on the person – five to six millimeters, we’ll have to intervene. But you can completely obstruct the kidney for up to a month and, if the stone is able to pass on its own, they’ve caused no harm to the kidney.

How to prevent kidney stones: Encouraging water intake will be a general preventive.   I generally encourage someone who is a stone former to drink about two to three liters a day so that they’re make two liters of urine in the daytime. The other easier monitor is whenever someone empties their bladder, we’d like to see the urine be light, pale yellow or clear.

Other risk factors for kidney stones: Some congenital things we can inherit from our families. It can have to do with absorption of calcium. People who have calcium restricted diets actually do form more stones. The reality is a lot of this plays into salt. Certainly, salt is ubiquitous in our environment between diet drinks and fast foods, chips and pretzels and everything. So, in someone who is forming stones or has that family tendency, hydration and avoidance of salt is my best recommendation.

For more information: 

6 Easy Ways to Prevent Kidney Stones 

Kidney Stones: Causes, Symptoms, and Treatments

Sam Baker is KERA's senior editor and local host for Morning Edition. The native of Beaumont, Texas, also edits and produces radio commentaries and Vital Signs, a series that's part of the station's Breakthroughs initiative. He also was the longtime host of KERA 13’s Emmy Award-winning public affairs program On the Record. He also won an Emmy in 2008 for KERA’s Sharing the Power: A Voter’s Voice Special, and has earned honors from the Associated Press and the Public Radio News Directors Inc.