Calcium oxalate crystals are the main chemical constituents of kidney stones most commonly found in the kidneys. What are the causes and how to eliminate them?
What is Calcium Oxalate?
Causes of Calcium Oxalate Stones
Currently, 80% of kidney stones are calculs d’oxalate de calcium. Science believes that the production of calcium oxalate is a pathology of civilization.
Before, the calculations were located at the level of the bladder and were composed of both phosphorus and calcium. Today, the calculations are more in the kidneys. This development is mainly due to our diet, because we eat and drink a lot of sugary or salt-rich products, dairy products, proteins, which promotes the appearance of calcium oxalate stones. “We sometimes make the mistake of believing that if we have kidney stones, it is because we eat too many dairy products, but they are mainly due to the fact that we do not drink enough water. , insists doctor Karim Ferhi. “People also have a reflex tendency to stop eating dairy products but what they don’t know is when lowering their blood calcium levels, they increase the oxalate level which promotes stone formation.”
The recommended amount of calcium intake per day is 1000 milligrams. For example, plain yogurt contains 138 mg of calcium. Don’t forget to drink at least one and a half to two liters of spring water (beware of water with too much calcium) per day, in order to avoid the risk of stone formation. The water effectively prevents the aggregation of the crystals between them.
Some foods are high in oxalate, such as black tea, chocolate, sorrel or rhubarb. So we limit them as much as possible.
Conversely, other foods such as citrus fruits, tomato juice, foods rich in potassium (avocados, bananas, artichokes, melons), foods rich in magnesium and Vitamin B6 (pistachios, leafy green vegetables), prevent oxalate and calcium from clumping together and forming a stone. You can eat them without moderation!
Specialists also recommend drinking a liter of water with the addition of lemon juice to make urine alkaline and increase potassium and citrate levels and thus prevent stone formation.
Who are the people at risk?
Calcium oxalate stones are more common in men than in women (about 2 men for 1 woman, most often between 20 and 60 years old (source: American Hospital)
People with hyperparathyroidism may have a predisposition to calcium oxalate stones. “Their hypersecretion of parathormone (hormone synthesized by the parathyroid glands) increases the level of calcium in the blood which promotes calculus”, says the urologist.
People who have suffered removal of part of the intestine may also be prone to this type of stones because the operation performed decreases the reabsorption of potassium and citrate.
People with obesity are also among the subjects at risk because of the bypass placed by gastroplasty or even people who have a deficiency in vitamins B12 or B9, which causes a decrease in their potassium and citrate levels.
What are the symptoms of renal colitis?
Renal colic is very painful. They begin when the calculation moves from the kidney and then comes to block in the canal of the ureter. They can be complicated by causing infections accompanied by fever, kidney failure if the kidney no longer works. Sometimes it is necessary to operate urgently. Paradoxically, there are people who carry stones without feeling the slightest symptom.
“A stone of 2 to 3 mm can get stuck for a few days and then pass on its own in the urine, indicates the urologist. Some stones of 4 to 5 mm can remain in the kidney indefinitely, however, larger stones (1 to 2 cm) can carry germs, cause infections and alter kidney function. When the urologist finds a stone of this size, even if it is asymptomatic, he will seek to eliminate it”.
It is possible to promote the dissolution of calcium oxalate crystals and therefore avoid kidney stones via the alkalinization of urine. To make the urine more alkaline (with an alkaline pH), it is possible to consume foods or drinks rich in citric acid (Vichy water for example) or by taking a medicine rich in citric acid. But this alkalinization takes time: at least several weeks. Other solutions: surgical treatments, when kidney stones do not eliminate spontaneously. We find, as surgeries: the lithotritie extracorporelle, ureteroscopy (flexible or rigid, with or without the use of a laser) or the percutaneous surgery.
What are the types of intervention?
There are four types:
- Extracorporeal lithotripsy consists of sending ultrasound directly to the kidney through the abdominal wall. The shock waves from lithotripsy will fragment the stone. This technique is suitable for stones with a size between 4 mm and 10 mm. “Patients are not hospitalized and it sometimes takes 2 to 3 sessions to successfully fragment a stone”specifies the specialist;
- Ureteroscopy flexible is performed on an outpatient basis (entering the hospital in the morning, leaving in the evening) and under general anesthesia. Equipped with a special device called the ureteroscope, the surgeon-urologist accesses the ureter through the urethra and bladder. Once in the ureter, it can reach the kidney and then fragment the laser stone. He recovers the various fragments then sets up a small probe for a few days to allow the elimination of the fragments and promote healing of the ureter;
- Percutaneous nephrolithotomy (PCNL) consists in carrying out under general anesthesia, in the event of very large calculations (more than 2 cm), of mini-incisions at the level of the kidney through the skin and the wall of the back. Then, using a device called a nephroscope, the surgeon will fragment the stone or stones with a laser and recover the different fragments, leaving a drain in place for 24 to 48 hours. “Percutaneous nephrolithotomy is a more morbid intervention (resulting in more complications) than that involving ureteroscopy increasingly used in this indication, says Dr. Karim Ferhi. You can check the website Emergency Calculation Pariscreated by urologists in the Paris region, which allows people affected by kidney stones to be taken care of until the possible intervention and to benefit from dietary care.advises Dr. Karim Ferhi.
- Open surgery is used in case of large kidney stones. The operation consists of opening the kidney to retrieve the stone. “These stones, called coralliform stones (some can reach the size of the kidney) are quite rare and more frequent in Africa or Asia. reveals the specialist. “This technique is, today, little practiced”.
It is reassuring to know that 90% of stones are eliminated spontaneously and only 10% require surgery. The calculations eliminated spontaneously (sometimes up to 5 to 6 mm) cause renal colic that can last half an hour. Some of these crises require a visit to the emergency room. The patient is kept for a few hours, receives a treatment of non-steroidal anti-inflammatory drugs which make it possible to soothe the pain while dilating the ureter in order to promote the passage of the stone. “The patient must, at the end of the elimination of the calculation, consult a urologist who, thanks to a scanner, will check if the calculation has been completely eliminated. says Dr. Karim Ferhi. “He will put in place hygiene and dietary measures if necessary”.
The diagnosis, initially, is carried out thanks to a urinary dipstick which makes it possible to detect the presence of blood in the urine. Associated with lower back pain that radiates to the genitals, it could be renal colic. “Despite everything, the best examination for diagnosing kidney stones remains the non-injected abdominal CT scan”. recommends Dr. Karim Ferhi. “But, since this type of device is not available everywhere, it is also possible to perform an X-ray combined with a kidney ultrasound to check for the presence of kidney stones”.
To avoid the formation of kidney stones caused by calcium oxalate crystals, it is advisable to limiting the consumption of certain foods that promote oxalate formation and prevent the urinary system from working properly. The following foods should therefore be avoided, or at least consumed in moderation:
- Rhubarb, spinach, celery, beets, strawberries, nuts, nut or peanut butter, chocolate and cocoa, black tea, soy products, animal protein (consume normal way).
Attention should also be paid to do not consume too much sodium, i.e. no more than 2000 mg per day, which tends to increase the excretion of calcium in the urine. We therefore ease off on industrial foods, often high in salt, as well as cheeses and cold meats, or even smoked foods (salmon, ham, etc.).
We will make sure to have a fetch and calcium enough each day (found in dairy products and in particular hard cheeses, canned fish, legumes, green vegetables and certain fruits), and to drink enough water (minimum 1.5 liters 2 liters of water or infusion per day).
Another point: make sure you have a consumption of potassium sufficient. Potassium is found in fruits and vegetables and certain cereals such as avocado, banana, melon, peach, artichoke, squash, legumes, potato with skin, whole cereals, vegetables green leaves.
The vitamin B6 and magnesium, as explained above, help solubilize or dissolve calcium oxalate crystals, which limits the risk of kidney stone formation. Vitamin B6 and magnesium are found in tuna, salmon, cod, pistachios, sunflower, flax and chia seeds, bananas, leafy vegetables.
Food rich in citric acid also make it possible to make the pH of the urine alkaline, and therefore to reduce the formation of kidney stones. Citric acid is found in lemon or orange.
