Your Health Matters

More women seem to be getting painful kidney stones than ever before. Could it be their diet?

Urology has always been a man's field for both doctors and patients. (The urologist is to the man what the gynecologist is to the woman). Serious "plumbing problems" requiring a specialist's expertise are simply less common among women than men.

Kidney experts in the United States and Europe have begun to notice a troubling trend: The number of women getting excruciating kidney stones (renal calculi) seems to be on the rise.

A decade ago, about 450,000 men in the United States and a third as many women periodically suffered from stones- jagged burrs of calcium and other crystallized minerals that scrape and terrorize as they descend from the kidney through narrow byways of the urinary tract. Today's prevalence is closer to a million. Athird of cases require hospitalization, and while men still fall victim more often, women are catching up, says stone specialist Glenn Preminger of Duke University in Durham, North Carolina.

"Nobody's certain yet how big the shift is or what's behind it," Preminger says. "There are probably at least several factors, but in my opinion one of the best places to look would be changes in the female diet."

In 90 percent of cases, there is no identifiable cause for kidney stones. Stone formation is usually the result of many factors working together in a susceptible person. It is more likely to occur during middle age. Stones may be related to inherited disorders such as gout, or to metabolic problems involving the bowels or kidneys. They are more frequent in people who live in hot climates.

Stones may form due to being bedridden, excessive fluid loss through sweating, diminished intake of water, or a diet high in protein. Certain metabolic disorders as well as disease that result into too much calcium in the blood (for example, a type of cancer called multiple myeloma or hormonal disorder, hyperparathyroidism) can cause kidney stones. Also, overuse of sodium bicarbonate, and calcium supplements.

Once you've had one stone, you're likely to get more. The strongest predisposing influence- a family history of the disorder- triples your risk and can't be altered.

GET PLENTY OF CALCIUM, BUT… There are several types of kidney stones, but more than 80 percent have calcium as the leading constituent. The most common type: an amalgam of calcium and a salt called oxalate. Some doctors still advise patients to avoid dairy products, but experts say that's a bad idea. Studies published in the last two decades by Harvard School of Medicine and the Institute of Urology in London have shown that a diet low in calcium actually boosts the likelihood of stone formation, perhaps because it saps calcium from the skeleton and sends it into the urine.

In 1997, the National Academy of Sciences for the first time set a recommended upper limit on calcium of 2,500 mg a day for all adults, partly because of the risk of kidney stones increases when levels of the mineral are higher. Just don't go overboard! Take them with a meal and drink plenty of water.

GO EASY ON THE MEAT… Epidemiologists have long recognized that the more meat, fish, poultry, or eggs a nation consumes, the higher its incidence of kidney stones. The most dramatic evidence comes from Japan: 30 years ago, when meat and fish were considered flavorings, not entrees, kidney stones were almost unheard of. Today the Japanese eat much more the way Americans do and are nearly as likely to get stones.

Meat consumption also cuts the body's production of urinary citrate, a natural inhibitor of stones. Lastly, animal protein ups production of uric acid, which when concentrated, can crystallize to form a urinary pebble.

I don't mean to exaggerate the problem. The healthy kidney is a wondrous filter, and individuals vary widely in the amount of meat they can handle. But be warned: Experts say the high protein- low carbohydrate diets currently popular almost certainly increase the risk of stones for some people, most of whom won't know they're susceptible until their first attack. And since sodium increases calcium excretion, too, cut back on salt.

The vast majority of Americans need to gobble more servings of fruit and vegetables, not fewer. DRINK MORE WATER… this sounds too simple to be true: Dehydration fosters stones, (also other problems that you don't need). Everyone needs eight to ten glasses of water a day- your body will adjust!

Need more info? The Web site for the National Institute for Diabetes & Digestive & Kidney Diseases (www.niddk.nih.gov) offers links to support groups and the latest research.

Claudia Parks, RN, is a former doctor's office and emergency room nurse and retired as an educator from Fulton County Schools. She writes Your Health Matters as a public service; the information here is designed to help you make informed choices about your health. It is not intended as a substitute for the advice of your physician. Claudia and her husband make their home in the beautiful north Georgia Mountains, near Blairsville. Claudia can be reached at yhm@windstream.net