Kidney stones, commonly known as “kidney stones”, are crystals that form in the kidneys and can cause severe pain.
Find out everything you need to know about this disease in this sheet.
Kidney stones, what are they?
Kidney stones, commonly known as “kidney stones”, are hard crystals that form in the kidneys and can cause severe pain.
Doctors use the term urolithiasis to refer to these crystals, which can also be found in the rest of the urinary tract: in the bladder, urethra, or ureters (see diagram).
In nearly 90% of cases, urinary stones form inside a kidney. Their size varies, ranging from a few millimeters to several centimeters in diameter. Most of them (80%) are eliminated spontaneously by passing through the various ducts of the urinary system and cause few symptoms.
However, the ureters, located between the kidneys and the bladder, are very small caliber tubes. A stone formed in the kidney, which is in transit towards the bladder, can easily obstruct a ureter and thus cause severe pain. This is called renal colic.
The different types of calculations
The chemical makeup of the stone depends on the cause, but the majority of kidney stones contain calcium. Urine tests and an analysis of the recovered stones make it possible to know their composition.
Calculus-based on calcium
They account for about 80% of all kidney stones. They include calculations based on calcium oxalate (the most common), calcium phosphate, or a mixture of the two.
They are caused by dehydration, excessive intake of vitamin D, certain diseases and medications, hereditary factors, or a diet that is too high in oxalate (see Diet in the Prevention section).
Struvite stones (or ammonium-magnesium phosphate)
They are linked to chronic or recurrent urinary tract infections of bacterial origin and represent approximately 10% of cases1. Unlike other types of stones, they are more common in women than in men. Often they form in people who have a bladder catheter.
Uric acid stones
They represent 5 to 10% of kidney stones. They form due to an abnormally high concentration of uric acid in the urine. People with gout or receiving chemotherapy are more prone to suffer from it. They can also be caused by an infection.
This form is the rarest. In all cases, their formation is attributable to cystinuria, a genetic abnormality that leads to the excretion of an excessive amount of cystine (an amino acid) by the kidneys. This type of calculation can occur from childhood.
Who is affected by kidney stones?
Kidney stones are very common, and their prevalence seems to have increased over the past 30 years. From 5% to 10% of individuals will experience an attack of renal colic during their lifetime.
Kidney stones occur more frequently in the 40s. They are twice as common in men as in women. Some children can also be affected.
More than half of people who have already had a stone will have it again within 10 years of the first attack. Prevention is therefore very important.
Causes of calculations
The calculations are the result of the crystallization of mineral salts and acids present in too high a concentration in the urine. The process is the same as that observed in water containing a lot of mineral salts: beyond a certain concentration, the salts begin to crystallize.
Kidney stones can be the consequence of a large number of factors. Most often, they are due to a lack of dilution of the urine, that is to say too little water consumption.
An unbalanced diet, too rich in sugar or protein, can also be the cause. In many cases, however, there is no specific cause that can explain the formation of stones.
More rarely, an infection, certain medications, a genetic disease (such as cystic fibrosis or hyperoxaluria), or metabolic disease (such as diabetes) can lead to the formation of urinary stones. Similarly, malformations of the urinary tract may be involved, especially in children.
Possible Complications of Kidney Stones
Complications are rather rare if the calculations are well cared for. However, it can happen that in addition to an obstruction of a ureter by a calculation, an infection settles.
This can lead to a blood infection (sepsis) which will require emergency intervention. Another situation that can become serious is when a person with only one kidney has renal colic.
Important: The health risks associated with kidney stones are great; it is very important to be properly monitored by a doctor.
Symptoms of kidney stones (renal lithiasis) include sudden, severe pain in the back.
Discover the complete list in our fact sheet.
Symptoms of Kidney Stones
- Sudden, severe pain in the back (on one side, below the ribs), radiating down the lower abdomen and into the groin, and often to the sexual area, to a testicle, or to the vulva;
The pain can last for a few minutes or a few hours. It is not necessarily continuous, but it can become unbearably intense.
- nausea and vomiting;
- blood in the urine (not always visible to the naked eye) or cloudy urine;
- sometimes an urgent and frequent urge to urinate;
- in case of concomitant urinary tract infection, fortunately not systematic, one also feels a burning sensation when urinating, as well as a frequent need to urinate. You may also have a fever and chills.
Many people have kidney stones without even knowing it because they don’t cause any symptoms as such unless they block a ureter or are associated with an infection. It happens that one discovers the presence of urolithiasis during an X-ray examination carried out for another reason.
People at risk of kidney stones (urolithiasis) are, among others, people who have already had one or more kidney stones.
Check out the full list here.
People at risk for kidney stones
- People who have already had one or more kidney stones;
- people who have a family history of kidney stones;
- men more than women;
- people living in countries with hot and dry climates or who work in very hot environments (in commercial kitchens for example);
- people with high blood pressure. This doubles the risk of kidney stones 2 ;
- people with type 2 diabetes;
- people suffering from obesity;
- people with certain metabolic diseases;
For example, cystinuria (too much cystine in the urine), celiac disease, hyperoxaluria (too much oxalate in the urine), hypercalciuria (too much calcium in the urine), tubular acidosis kidney disease (which causes very acidic urine) or hyperparathyroidism.
- people prone to gout attacks;
- people who have recurrent urinary tract infections;
- people with inflammatory bowel disease, such as Crohn’s disease, which increases oxalate absorption.
Risk factors promote the development of kidney stones in some people.
Discover the complete list of these factors in this sheet.
Risk factors for kidney stones
These factors mainly concern people at risk, especially those who have already suffered from kidney stones:
- poor hydration;
Drinking little decreases the volume of urine, therefore, concentrating the salts in the urine and increasing the risk of crystallization.
- physical inactivity ;
The lack of physical activity causes a gradual loss of bone mass, therefore the release of calcium.
- taking certain medications;
Taking diuretics (including triamterene) or calcium-based antacids, for example, can increase the risk of developing kidney stones.
Sulfonamides and certain antivirals such as indinavir also increase the risk of lithiasis. People at risk should ask their doctor or pharmacist about their medication.
- a very salty or very high-sugar diet;
- a diet with an excess of protein;
Protein increases the levels of calcium, oxalate, and uric acid in the urine, and decreases the level of citrate (a protective factor against stones). Studies suggest that vegetarianism reduces the risk of kidney stones.
However, if the daily amount of protein is adequate, whether, of animal or vegetable origin, these do not influence the risk of kidney stones.
- a diet deficient in calcium.
Contrary to what one might think, dietary calcium (dairy products, canned fish with bones, fruits, green vegetables, legumes, and nuts) exerts a protective effect against kidney stones. Calcium supplements, taken with meals, may have the same effect, but taken alone may slightly increase the risk of kidney stones.
Measures to prevent kidney stones are hydration and diet.
Find out more about these different measures in this sheet.
How to prevent kidney stones?
Can kidney stones be prevented?
Preventive measures are primarily aimed at people at risk or those who have already had kidney stones. The following approaches may help, but to be more effective, it is best to determine the cause of the stones by undergoing various tests (see Medical Treatments).
Measures to reduce risk or prevent a recurrence
The best way to prevent kidney stones is to drink enough, which means at least 2 liters of water or other types of drinks every day (juice, broth, coffee, etc.). Water is preferred.
It is necessary to think of hydrating more when one makes intense physical efforts (the contribution of liquid must then be at least 3 liters per day) and during the summer season. People who live in a hot and dry climate should drink more.
A simple way to tell if you are getting enough hydration is to look at the color of your urine: it should be colorless or pale yellow (except in the case of people who have taken vitamin B supplements, which temporarily give urine a bright yellow color).
Experts at the Mayo Clinic recommend that people who are at risk for or have had stones in the past, drink a glass of homemade lemonade every day.
Lemon increases the amount of citrate (a substance that helps prevent stone formation) in the urine. Several studies have confirmed the interest of orange juice, tomato, or lemon, rich in citrate, to prevent the formation of stones.
Some studies have also shown that reducing the consumption of sugary drinks (sodas) made it possible, in certain cases, to reduce the rate of renal colic.
Warning: it is better to abstain from drinking grapefruit juice. Two epidemiological studies have linked the daily consumption of 240 ml (1 cup) of grapefruit juice to the recurrent formation of kidney stones.
However, no test has been able to confirm these observations. As long as doubt persists on this subject, it is best not to consume it, at least on a regular basis.
Reduce ingestion of oxalate-rich foods. People who have had calcium oxalate stones in the past should limit their intake of foods high in calcium oxalate. Here is a list of the foods richest in oxalate: spinach, rhubarb, beets, Swiss chard, peanuts, chocolate, tea, wheat germ, okra (okra), potato sweet, and soybean (soya). To find out more, ask a dietitian.
Maintain a good nutritional intake of calcium. The ingestion of calcium-rich foods would have a protective effect on kidney stones.
You just have to make sure you respect the recommended calcium intake (see our Calcium sheet). Ask your doctor or consult a dietitian if necessary. To find out if you’re getting enough calcium, use our interactive calculator.
Consume foods high in potassium. Potassium reduces calcium excretion. The best way to increase your potassium intake is to eat plenty of fruits and vegetables, most of which contain them. Those that contain the most are the potato (with skin), cantaloupe, avocado, lima bean, and banana.
Eat enough fiber. Bran is a rich source of insoluble fiber which reduces the absorption of calcium in the intestine, thus the level of calcium in the urine. People who experience recurrent attacks of kidney stones and do not eat enough fiber may benefit from consuming more. However, the studies conducted to date contradict each other on this subject.
To prevent stone recurrences, the doctor may prescribe various medications or supplements that vary depending on the type of stone (thiazide diuretics, allopurinol, potassium citrate, etc.).
Caution with certain supplements
Since the prolonged intake of high doses of vitamin D can cause kidney stones, it is advisable to consult a doctor before using vitamin D supplements. Vitamin D intake influences blood calcium levels.
The basic treatment is established according to the results of various medical tests (urine analysis, blood analysis, etc.), good hydration, etc.
Check them out in full below.
How to treat kidney stones?
The basic treatment is established according to the results of the various medical tests that the doctor proposes:
- a urinalysis to check for blood and crystals in the urine, and to determine its pH;
- analyzing a retrieved stone to determine its type;
- a blood test to check the state of kidney function or detect a metabolic abnormality;
- a CT scan of the kidneys, ureters, and bladder, which shows most stones.
Staying hydrated is basic stone prevention, but only when the pain is less severe. Indeed, when the pain is very intense, during the attack of renal colic, you should not drink. Because the calculation can be blocked in a ureter, preventing urine from passing. So drinking would increase the pressure in the ureter, and therefore the pain.
The majority of stones (especially if their diameter is less than 7 mm or 80% of stones) are eliminated on their own within 6 weeks of their formation, particularly if the person consumes a lot of water.
During this period, doctors usually recommend drinking about 3 liters of water or other types of beverages per day.
Renal colic is extremely painful. Pain relief may be necessary if it persists for several hours. Non-steroidal anti-inflammatory drugs, or opioids, can be administered intravenously in the hospital when the crisis is very violent.
If the condition is less painful, the person can stay at home under medical supervision.
She can relieve her pain by taking an analgesic such as paracetamol or acetaminophen (Tylenol, Doliprane) until the stone is evacuated. Heat also helps to relieve pain (hot baths, warm and moist compresses).
In the case of struvite stones, it is important to treat the urinary tract infection. It is also necessary to discover and eliminate as far as possible the factors which predispose to infections.
In the event of an infectious sign or pain not relieved by analgesics, an internal probe called a double J probe or JJ probe must be fitted urgently.
This is a small tube that the doctor enters through the urethra, passes through the bladder, and then places between the bladder and the kidney in each of the ureters. This JJ catheter allows urine to pass around the stone, or pushes the stone back up into the kidney, where it can later be fragmented.
In case of infection, there is an emergency: the urine must be drained urgently, so as not to leave this infected urine in the kidney as this would damage it or could cause septic shock (sepsis).
If there is no infection, or after placement of a JJ catheter if the stone is not evacuated, it will need to be fragmented, i.e. broken into small pieces or extracted surgically using one of the following techniques:
It is the most frequent intervention thanks to new technologies, the flexible ureteroscope, the laser, and the surgical material (tweezers or small baskets) allowing to go to recover the fragments of the calculation or to take it out in one go. Ureteroscopy is performed under general anesthesia.
It consists of introducing a tube equipped with a mini camera (called a ureteroscope) through the urethra towards the bladder, up to the ureter. The calculations are then fragmented or removed intact.
The ureter is sometimes injured either by the technique or by the calculation if it is irregular and sharp. In this case, the JJ catheter can be left in place after the operation to allow the ureter to heal. The use of analgesics or antispasmodics helps relieve pain.
Various lifestyle habits and other treatments can be implemented to prevent stones from forming in the future. See the Prevention section.
Extracorporeal shock wave lithotripsy
It is an external technique requiring neither opening the body nor entering inside our organism, the shock waves diffusing through the skin. During this procedure, ultrasound is directed directly at the stone. They break it up, and the small pieces can be eliminated through the urinary system.
This procedure can be performed on an outpatient basis, so without hospitalization. The risk of the shock wave method is to cause a hematoma, the shocks being relatively violent, not succeeding in fragmenting it entirely, and requiring fairly long sessions.
The choice of method depends on the stones, their location, the type of stone, their size, etc.
This technique was a revolution, but it is practiced less and less in favor of flexible uteroscopy. It is used if the stone is very large or if it is positioned in such a way that it cannot be fragmented by extracorporeal lithotripsy.
The doctor makes an incision in the back and installs a viewing tube and an instrument called a nephroscope in the kidney to extract the stone. If the stone is too large, it can be broken up using a laser or electrical energy. Typically, the person undergoing this procedure stays in the hospital for several days.
possible to treat it in a more natural way.
Check out the full list here.
Complementary approaches in the case of kidney stones
As magnesium increases the solubility of calcium in urine, it appears to have a preventive effect on the formation of kidney stones. It also reduces the intestinal absorption of oxalate.
The authors of a review of clinical trials concluded that the oxide and hydroxide salts of magnesium produced variable results which would be attributable to the low absorption of these forms of magnesium.
On the other hand, in a double-blind study of 67 subjects, a mixture of potassium and magnesium administered as citrate was significantly more effective than a placebo in preventing the recurrence of kidney stones for 3 years.
Pumpkin seeds appear to both reduce the concentration of substances in urine that cause the stone formation and increase the concentration of substances that inhibit stone formation.
Two studies carried out in Thailand concluded with the preventive effectiveness of pumpkin seeds eaten as a snack every day in children and adolescents prone to kidney stones.
Some preliminary studies suggest that taking fish oils and evening primrose oil would have some preventive effects. An uncontrolled study of 88 patients with calcium kidney stones who consumed 1,800 mg of fish oils (EPA) daily for 3 or 18 months found a decrease in urinary calcium levels.
However, this hypothesis tends to be invalidated by the analysis of the results of 3 epidemiological studies conducted among tens of thousands of men and women. No link was then noticed between the dietary intake of various fatty acids and the risk of kidney stones.
According to a large epidemiological study (Nurses’ Health Study – 80,000 nurses), a high intake of vitamin B6 (pyridoxine), whether through diet or supplementation, or both, is inversely associated with the risk of suffering from kidney stones in women. This correlation was not found in men.
Like magnesium, vitamin B6 helps maintain calcium oxalate in the soluble phase.
Asparagus (Asparagus officinalis)
These plants would have the ability to increase the urinary flow (so-called diuretic effect). This is why the German Commission E recognizes their usefulness in preventing the formation of kidney stones.
- asparagus: drink one infusion per day containing 45 to 60 g of asparagus rhizomes infused in 150 ml of boiling water. Another source indicates that it is good, too, to consume them in the form of food;
- nettle: consult the Nettle sheet;
- parsley: consume a maximum of 6 g per day of parsley leaves and roots (parsley can be taken as an infusion: infuse 2 g in 150 ml of boiling water and drink 3 times a day);
- dandelion: consult the Dandelion sheet;
- goldenrod: take 6 to 12 g of goldenrod daily as an infusion (infuse 3 g of the herb in 150 ml of boiling water).
Acupuncture could reduce the pain associated with renal colic34. In addition, it would help reduce anxiety before shock wave lithotripsy treatment.
Thus, a study of 56 patients waiting to receive lithotripsy to pulverize their kidney stones indicates that those who received acupuncture treatment were less anxious at the time of the intervention than those who had received the placebo. In addition, these patients required a smaller amount of analgesic during lithotripsy.
Nettle (Nettle dioica), parsley (Petroselinum crispum), prêle des champs (Equisetum arvense), verge d’or (Solidago virgaurea)
Commission E approves the use of these plants in the treatment of kidney stones.
- nettle: consult the Nettle sheet;
- parsley: consume a maximum of 6 g per day of parsley leaves and roots (parsley can be taken as an infusion: infuse 2 g in 150 ml of boiling water and drink three times a day);
- field horsetail: consult the field horsetail sheet;
- goldenrod: take 6 to 12 g of goldenrod daily as an infusion (infuse 3 g of herbs in 150 ml of boiling water).
Butterbur (Petasites hybridus)
Commission E recognizes that butterbur relieves pain due to spasms of the urinary tract in case of stones.
Dosage: take 50 to 100 mg of standardized extract (ie 7.5 to 15 mg of petasin), 2 times a day, with meals.
The preparation Te Xiao Pai Shi Wan is prescribed to treat attacks of renal colic. To our knowledge, no scientific study has been done to confirm the effectiveness of this preparation.
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