Romancing the stones
Researchers study bacteria in effort to stem unpredictable ailment
It probably won’t kill you, even if it feels that way when a kidney stone is scraping through your body.
The ailment that afflicts one in 10 Canadians typically announces itself suddenly with a punch of abdominal pain that lands people in emergency rooms wondering what hit them.
“It’s a benign disease that costs a lot of money,” says microbiologist Dirk Lange, director of basic science research at the Stone Centre at Vancouver General Hospital. “Patients keep coming back, reporting to the emergency room for various reasons: maybe they’re in pain, maybe the urine flow is obstructed or stopped, which causes damage to the kidneys.”
That’s why Stone Centre researchers are tackling a new line of inquiry to find out which of the thousands of species of bacteria in the human gut can help stop kidney stones from growing in the first place.
Lange has the unglamorous yet fascinating job of using genetic sequencing techniques to identify bacteria in stool samples from people with and without kidney stones. He’s building on research that has found about 70 per cent of kidney stone sufferers don’t have a bacteria in their gut that breaks down oxalates, a substance produced in the liver and also derived from foods as diverse as spinach, chocolate and french fries.
At the same time, about 70 per cent of people who do not have kidney stones carry the bug called Oxalobacter formigenes.
Since the link is not 100 per cent, Lange and his colleagues are looking for the missing pieces in a largely unexplored area of research on how human microbiota — that mass of bacteria in the human digestive system that varies from person to person — affects kidney stones.
The goal is to identify the “good” bacteria so patients might one day be able to take it in a pill or eat it in yogurt. Stones form when waste chemicals processed by the kidneys crystallize and stick together to create a jagged shape that might be small enough to pass naturally — but not painlessly — through narrow vessels called ureters to the bladder and then the urethra. Anything larger than a pea must be shattered with shock waves so it can be expelled through the bladder, or surgically removed.
Carolyn Abramson, 70, of Abbotsford had an operation two years ago to cut out a “goliath” kidney stone the size of the end of her thumb. That was more than 30 years after she naturally passed two smaller stones.
“You cannot predict when you are going to have an attack of kidney stones and when you do, it’s debilitating,” says Abramson, who will speak along with Stone Centre specialists at a public talk Tuesday at VGH.
She and her husband are taking part in the research, dutifully providing bodily fluids, and solids, for analysis.
“He doesn’t get stones, so the question is: What’s the difference? We eat the same thing, we drink the same water yet I’ve got all kinds of kidney stones and he doesn’t have any,” Abramson said in phone interview.
“A friend asked me once if it’s more painful than childbirth. I said, ‘It took me three days to have my daughter, and kidney stones were worse.’”
While the chemical components that build up as crystals in the kidneys are known, a way to prevent the process is not.
The growing number of overweight North Americans with metabolic syndrome — changes in the way our bodies use insulin while digesting food — is blamed for the rising incidence in kidney stones over the last 40 years.
“Obesity is probably one of the reasons that kidney stone disease is on the rise,” Lange said.
“And the other, believe it or not, is climate change. As temperatures increase, the rate of dehydration increases as well.”
Drinking two to three litres of water a day is the most effective tool in preventing kidney stones because it dilutes the body’s waste so oxalates and calcium don’t stick together to form the most common kind of stones.
Doctors suggest moderating high-oxalate foods, even the ones we consider healthy like rhubarb, beets and sweet potatoes.
More importantly, cut back on meat, salt and processed foods. A diet that’s good for heart health is good for kidney stones.