Why kidney stones form and how to prevent them

The pain of passing a kidney stone is often described as worse than giving childbirth.  Other descriptive terms range from excruciating, agonizing, miserable and just plain intolerable. 

Kidney stone disease (also known as urolithiasis) causes more than one million trips to theemergency room by people in the United States each year.   

Keeping the kidneys free and clear of kidney stones is important. These bean-shaped organs located on the back side below the rib cage sitting opposite each other have a vital job to do in keeping our body healthy.  They help keep the composition of our blood stable allowing the body to function properly. Buildup of wastes and extra fluid in the body is prevented thanks to the kidneys. They also keep levels of electrolytes (sodium, potassium, and phosphate) stable, and make hormones helping regulate blood pressure, make red blood cells, and keep our bones strong.

In addition the kidneys do an amazing job of filtering about 120 to 150 quarts of blood to produce about 1 to 2 quarts of urine, composed of wastes and extra fluid we pass each day.

As far back as over two thousand years ago, kidney stone sufferers have had to endure the pain of the passage of a stone.  In 400 B.C. Hippocrates referred to them as “first disease of the kidneys” making him one of the first to make the connection between urinary obstruction and pain.  He wrote:

“An acute pain is felt in the kidney, the loins, the flank and the testis of the affected side; the patient passes urine frequently; gradually the urine is suppressed.  With the urine, sand is passed; as the sand passes along the urethra, it causes severe pain which is relieved when it is expelled; then the same sufferings begin again.”

Hippocrates observation still holds true today but what exactly is a kidney stone and can they be prevented?

What is a kidney stone?

A kidney stone is a piece of stone-like material that forms on the walls of the kidney when substances that are normally found in the urine become highly concentrated.  Sometimes a kidney stone will stay in the kidney while others will travel down the urinary tract. 

Generally most kidney stones are small enough to pass through the urinary system without any pain.  But if the stone is large enough it can cause urinary blockage causing extreme pain and will require treatment or surgery.

Anyone can get a kidney stone but some people are more likely to develop them than others.  Men are more likely to have kidney stones than women and they are more common in non-Hispanic white people than in black people and Mexican Americans.  People who are overweight to obese have a higher risk than those who are normal weight.  Those with a family history of kidney stones are also more susceptible.  About 8.8 percent or one in 11 people in the United States have had a kidney stone.

Causes of kidney stones

When substances in the urine such as calcium, oxalate, and phosphorus become highly concentrated, a kidney stone can form.  There can be several reasons why a kidney stone forms putting people at an increased risk for stone formation:

·Not consuming enough fluids, particularly water

·Certain foods may promote stone formation in people who are susceptible

· Hypercalciuria – a condition that runs in families in which urine contains unusually large amounts of calcium. 

·Family history of kidney stones

·Cystic kidney diseases which are disorders that cause fluid-filled sacs to form on the kidneys

·Hyperparathyroidism – a condition in which the parathyroid glands release too much hormone, causing extra calcium in the blood.

·Gout – a disorder that causes painful swelling of the joints

·Blockage of the urinary tract

·Chronic inflammation of the bowel

·A history of gastrointestinal tract surgery

·Taking diuretics – medications that help the kidneys remove fluid from the body

·Calcium-based antacids

·The protease inhibitor indinavir (Crixivan) a medication used to treat HIV infection

·The anti-seizure drug topiramate (Topamax)

Dietary ways to treat kidney stones

There are several ways to prevent kidney stones specifically by our dietary habits.  One way is to consume enough fluids each day which can help prevent most types of kidney stones.  It is recommended to drink 2 to 3 liters or 8 to 16 cups of fluid a day. Doing so helps flush out unwanted substances and prevents urine from becoming too concentrated – remember, our urine should be a pale yellow color. 

Here are other dietary precautions to use to prevent kidney stone development:

·Reduce sodium by reducing intake of hot dogs, canned soups and vegetables, processed frozen foods, luncheon meats and fast food. 

·Reduce animal protein, such as meat, eggs, and fish to moderate portions of 3-4 ounces at a meal.

·Avoid foods high in oxalate such as spinach, rhubarb, nuts, wheat bran, dark beer, black tea, chocolate milk, beet greens and carrots.

·Get enough calcium from food.  Calcium from food does not increase the risk of calcium oxalate stones. In fact, too little calcium can cause oxalate levels to rise causing kidney stones.  Calcium in the digestive tract binds to oxalate from food keeping it from entering the blood and then the urinary tract, where it can form stones.  People who have formed a calcium oxalate stone should consume 800 milligrams of calcium each day however calcium supplements may increase the risk of calcium oxalate stones if they are not taken with food.

·If overweight to obese, lose weight as carrying extra weight can increase the risk of stone formation particularly uric acid stones. 

·Following the DASH diet has been shown to reduce the risk of kidney stones.