It’s summertime, the season of peak sunshine and warmth, and, for most of us, that’s a good thing. For an unfortunate and growing few, though, summer is the peak season for a condition that can cause excruciating pain: kidney stones.

Kidney stones, made from chemicals in urine, tend to make their presence known in the warmest months of the year. One likely reason is that people sweat more, don’t drink enough to make up for it, and end up with more concentrated urine, allowing crystals to form and grow into stones. In places where it’s fairly warm year-round, such as the southern United States, kidney stones are more common than in colder climes.

Around the world, the incidence of kidney stones is rising. In the United States, the lifetime risk of having at least one kidney stone is now about 10 percent, up from 3.8 percent in the 1970s, according to the National Kidney Foundation. Among possible reasons: the warming climate and the migration of people to warmer urban areas. But heat isn’t the whole story. The way we eat and drink and the rise of obesity and diabetes likely play roles, too.

From unnoticed to unbearable

Typical stones may be as small as a grain of sand or as large as a chickpea. More rarely, they can be as large as golf balls. A small stone may sit in your kidney unnoticed for months or years before it gets big enough or starts moving enough to cause trouble. Often, that happens when a stone moves from a kidney to a ureter, one of the tubes leading to the bladder. The stone may get stuck there, blocking urine flow or causing irritation as it makes its way through the ureter and bladder and out through the urethra. Once a stone becomes problematic, symptoms can start suddenly:

  • Intermittent mild to severe pain in the side, back, or groin for five to 15 minutes
  • Stomach pain, nausea, and vomiting
  • Blood in the urine
  • Fever, chills, and bad-smelling or cloudy urine
  • Kidney damage that may linger.

Diagnosis and treatment

If you show up in an emergency room or doctor’s office with a possible kidney stone, expect to get a CT scan, an ultrasound, or an x-ray to confirm the stone as well as its size and location. You also will get blood and urine tests to check for kidney function, levels of stone-forming substances, and infection.

Unless the stone is quite large or causing unmanageable pain or other complications, your doctor is likely to send you home to see if the stone will pass, which will happen within a few weeks in 80 percent of cases in which stones are no larger than 4 millimeters. Larger stones are less likely to pass. While some people will need prescription painkillers to get through the process, others will do fine with an over-the-counter anti-inflammatory painkiller. Naproxen sodium (Aleve) is a good choice. Anything that helps you relax, even a warm bath, can help. You may also get medication to relax the ureter or change the acidity of your urine.

Contrary to popular belief, studies have not found that drinking extra fluids after a stone forms helps it to pass, though extra fluids can help prevent future stones.

Advanced interventions

When stones appear unlikely to pass unaided or are causing complications, the next step is a procedure to remove or destroy them. There are several options:

  • Ureteroscopy. A small instrument, called a ureteroscope, is inserted through your urethra and bladder to reach the stone. Then, in most cases, a laser is used to break up the stone so it can be easily expelled.
  • Shockwave lithotripsy. For this procedure, you lie on a surgical table or in a tub of water while shockwaves are aimed at the stone to break it apart.
  • Percutaneous nephrolithotomy. This less-common procedure is used for large or irregularly shaped stones or in other special circumstances. A surgeon makes a small incision on the back, uses instruments to see and break up stones, then suctions out the fragments.

What can you do?

Anyone who’s ever suffered through a kidney stone shares one fervent wish: They never want to do it again. Yet, half will develop another stone within a few years. Those who’ve had two or more stones are at even higher risk. One reassuring fact: Most kidney stones can be prevented, no matter the season. See below to learn how.

Four kinds of kidney stones

Not all kidney stones have the same causes. Knowing which type you’re prone too can help you tailor your prevention plan.

  • Calcium oxalate. Most kidney stones form when calcium in urine combines with oxalate, a salt. Calcium oxalate stones make up as many as 85 percent of cases. They are linked to inadequate fluid intake and diets that are high in oxalates and salt but, paradoxically, low in calcium.
  • Uric acid. These stones are linked with conditions including type 2 diabetes, obesity, and gout and with diets high in animal protein.
  • Struvite. These stones occur mostly in women with chronic urinary tract infections. That’s because some bacteria secrete enzymes that make urine less acidic, allowing stones to form.
  • Cystine. These rare stones are found only in people with a genetic disorder called cystinuria that causes the kidneys to excrete excessive amino acids. They tend to recur.

8 Steps to prevent stones

  1. Drink up. Staying hydrated is important for everyone, but especially for people prone to kidney stones. Aim for 12 cups of fluid (96 ounces) every day. Water is better than sodas or tea. If you are sweating a lot, drink more.
  2. Get enough calcium. Even though the most common stones contain calcium, a calcium-rich diet helps prevent them. That’s because calcium in food binds with oxalates in your digestive tract, preventing these minerals from reaching high concentrations in your kidneys. Good sources include low-fat milk, cheese, and yogurt, sardines, and fortified cereals and juices. Calcium supplements may increase stone risk, but you can blunt that risk by choosing calcium citrate rather than calcium carbonate products. Taking them with food helps, too.
  3. Limit sodium to 2,000 milligrams per day. Excessive sodium leaches calcium from the bones and concentrates it in the urine. Watch out for the salt hidden in restaurant meals and processed foods, such as soups, bread, and sandwich meats.
  4. Limit foods that are high in oxalates. If you are prone to stones containing oxalate (see sidebar), your doctor may suggest that you limit foods such as strawberries, spinach, beets, nuts, organ meats, chocolate, tea, coffee, and cola.
  5. Limit animal protein to about 80 grams per day. Diets heavy in meat and seafood are linked with both calcium and uric acid stones (see sidebar).
  6. Watch out for sweeteners. High-fructose corn syrup, found in many foods and drinks, is linked with uric acid stones.
  7. Talk to your doctors about medications and supplements that might help prevent your type of stone. These can include pills or drinks containing citrate and medication to reduce uric acid levels. Some medications can increase your risk of kidney stones. Talk to your doctor or pharmacist to review all of the medications that you take.
  8. You can also try a home remedy to reduce your risk. Mix one-half cup of lemon juice with two quarts of water and drink throughout the day.

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