Kidney stones develop when dissolved minerals build up inside the kidneys. A low fluid consumption, dietary factors, and a person’s medical history may contribute to their development.
Kidney stones may be small and pass unnoticed through the urinary tract, but some grow to the size of a golf ball. Larger stones can cause severe pain as they leave the body.
Without treatment, kidney stones can lead to urinary problems, infections, and kidney damage.
Kidney stones are a common problem in the United States, and the incidence appears to be growing. Dietary factors and climate change may contribute to this increase, according to one study.
In this article, we look at how to recognize kidney stones and explain what to do if they occur.
Kidney stones do not always cause symptoms. A person may pass very small stones out of the body in the urine without being aware of them.
When symptoms appear, they commonly include:
- pain in the groin, the side of the abdomen, or both
- blood in the urine
- vomiting and nausea
- a urinary tract infection (UTI)
- fever and chills, if there is an infection
- an increased need to urinate
If kidney stones block the passage of urine, a kidney infection may result. The symptoms include:
- a fever and chills
- weakness and fatigue
- cloudy, foul-smelling urine
If a person has any of these symptoms, they should seek medical help at once.
When kidney stones remain inside the body, complications can develop.
If they block the tube that connects the kidney to the bladder, urine will not be able to pass out of the body. This dysfunction increases the risk of a UTI or kidney infection.
About 50% of people who have had a kidney stone develop another one within 5–7 years.
There are four different types of stone: calcium, uric acid, struvite, and cystine.
Calcium stones form when the kidneys retain the excess calcium that the muscles and bones do not use, rather than flushing it out of the body. The calcium combines with other waste products to form crystals, such as calcium oxalate, which clump together to make a stone.
Uric acid stones result from a lack of water in the body. Urine contains uric acid. When there is not enough water to dilute the uric acid, the urine becomes more acidic.
Struvite stones can form after a UTI. They consist of magnesium and ammonia.
Cystine stones develop when cystine, a substance present in the muscles, builds up in urine. These are rare.
The American Urological Association say that people who are susceptible to kidney stones should consume enough fluid to produce 2.5 liters (l), or about 85 ounces (oz), of urine each day. On average, this means consuming close to 3 l, or about 100 oz, of fluid a day. Not all of this needs to come from water.
Apart from dehydration, factors that increase the risk of kidney stones include:
- a family or personal history of kidney stones
- being aged 40 years or older, although they can sometimes affect children
- sex, as they are more common in males than females
- a diet that is high in protein and sodium
- a sedentary lifestyle
- high blood pressure
- recent surgery on the digestive system
- health conditions that affect how the body absorbs calcium, such as inflammatory bowel disease and chronic diarrhea
Various medications, such as allopurinol (Zyloprim) and topiramate (Topamax), can also increase the risk. People should check with their doctor if they have concerns about any medications they are taking.
Various tests can show whether a kidney stone is present.
- A physical examination may identify the kidneys as the source of pain.
- Urinalysis can reveal blood in the urine or signs of an infection.
- Blood tests can help identify complications.
- Imaging tests, such as a CT scan or ultrasound, will reveal any structural changes.
Imaging tests can help doctors determine:
- whether a stone is present
- the size and location of any stones
- whether there are any blockages
- the condition of the urinary tract
- whether complications have affected other organs
During pregnancy, an ultrasound is preferable to a CT scan, as it does not involve radiation.
Treatment will focus on managing symptoms and removing the stone. There are various ways to do this.
Treatment may involve:
- a high intake of fluids by mouth or intravenously
- pain relief medication
- medications to help speed up the passage of stones
Large stones may need other types of intervention, such as shock wave lithotripsy (SWL), ureteroscopy, or percutaneous nephrolithotomy (PCNL).
SWL involves the use of ultrasound waves to break the stone into smaller pieces to make it easier to pass.
If a doctor opts to use ureteroscopy, they will pass a long, thin tube through the person’s urethra as far as the ureter, which connects the bladder and the kidney. They will then use laser energy to break up the stone.
PCNL involves passing a long, thin instrument through the back and into the kidney, where it can break up or remove the stone using laser energy. This procedure requires general anesthesia.
There may be a risk of complications, such as an infection, after removing a large kidney stone. A doctor should explain the possible complications beforehand so that if any develop, a person can recognize the signs.
A person can usually treat small kidney stones at home.
A doctor may recommend:
- drinking plenty of fluid and waiting for the stone to pass
- using over-the-counter drugs to relieve pain and nausea
- taking alpha-blockers to help the stone pass more quickly
- avoiding salt and sodas
They may advise the person to continue to drink plenty of fluid after the stones have gone to prevent new ones from forming.
Some foods may benefit kidney health and help reduce the risk of kidney stones.
Herbs and spices
Guidelines from the American Family Physician (AFP) note that people have long used herbal remedies for kidney stones. However, there is uncertainty regarding their safety, effectiveness, and possible interactions with other drugs.
The AFP add, though, that:
- phytonutrients in green tea, berries, and turmeric may help prevent infection
- parsley may boost urine production
- Agropyron repens (couch grass) may help flush out the urinary tract
Proponents of natural remedies note that other foods and supplements that may help protect the kidneys include:
- vitamin B6 supplements
- pyridoxine supplements
Some research suggests that vitamin D deficiency is common among people with kidney stones, but there is not enough evidence to show that vitamin D supplements are safe or effective for preventing stones.
Do kidney beans help?
Some people drink kidney bean broth to help the stones pass.
People can make the broth by boiling the pods inside the beans for about 6 hours and then straining them. Once the liquid has cooled, they can consume some every 2 hours for 1–2 days.
However, it is important to note that there is no scientific evidence to confirm that this is effective.
Foods to avoid
Limiting foods that contain the following substances may help prevent stones from developing:
- sodium (salt)
- sugar, such as high fructose corn syrup
- vitamin C supplements
Oxalate is present in many common foods, such as:
- Swiss chard
However, people should not completely avoid foods containing oxalates, calcium, and protein, as they can have other nutritional benefits.
Kidney stones are not always preventable, but experts recommend that people reduce the overall risk by:
- drinking at least 2 l of water each day
- following a healthful diet
- doing regular exercise
For those with a higher risk of developing kidney stones, a doctor may make dietary recommendations or prescribe medication.
Kidney stones are a common problem. Not drinking enough fluid is a major causative factor, but dietary habits, obesity, and a sedentary lifestyle can all contribute.
Anyone who has symptoms of a kidney stone, urine infection, or kidney infection should seek medical advice to prevent complications from developing.