Urology – kidneys stones

What are kidney stones?

Kidney stones are pieces of hard material that forms in the kidneys when minerals in the urine become very concentrated. Small stones often pass through the body with mild discomfort, but large stones can be very painful and can even obstruct the urinary tract. Usually, a kidney stone starts as a small crystal-like material, and gradually builds up into a larger solid mass. Urine usually contains chemicals that prevent crystals from forming.
If the crystals remain small enough, they can pass through the urinary tract and out of the body without being noticed. However, when the crystals combine and form a kidney stone, it may stick to the lining of the kidney or settle in an area where urine cannot carry it out of the body. This is the third most common disease in urology, after urinary tract infection and prostate disease.

How are kidney stones formed?

There are two main factors that lead to kidney stones - either a low fluid content in the urine with an excessive amount of solid waste products, or a deficiency of substances in the urine that prevent the formation of stones. These conditions can cause the passage of crystals in the urine. 

How common are kidney stones?
Kidney stones affect up to 5% of the population, with a lifetime risk of passing a kidney stone being 8-10%. Over the last twenty years there has been a rise in the incident rate in many countries. Annually, 40 million Americans suffer from kidney stones. Turkey has a high percentage of kidney stone sufferers: 20% of men and 5-10% of women are expected to experience the condition at some stage of life.

What factors lead to the formation of kidney stones?

Kidney stones are not caused by a single cause, but rather occur as a consequence of a number of factors. Typically, metabolic and environmental factors have the greatest impact. Factors that play a role include heredity, gender, age, geographic location, climate, and occupation.

• Heredity: at least 25% of cases have genetic predisposition for this disease.
• Gender: stones occur 3 times more frequently in men than in women. The reason is the higher amount of the protective citrate hormone estrogen in female urine combined with lower levels of oxalate, which contributes to stone formation. Testosterone in men enhances oxalate production in the liver.
• Age: The disease is most common in people between the ages of 25 and 50. Symptoms usually begin in a person's 20s. Between 1 and 5% of cases occur in children.
• Geographical location: The disease is more common in mountainous, desert, and tropical regions.
• Climate: Risk is increased in hot climates. Excessive sweating without sufficient fluid intake increases the risk of stones. Therefore, the risk increases in summer. Sun exposure and increased vitamin D synthesis increase the amount of calcium in the blood.
• Profession: The occurrence of stones increases in people who work in hot conditions. For example, agricultural workers. Employees who work in a sitting position and people bedridden have an increased risk.
• Education: The risk of stone formation decreases with a higher level of education.
• Income level: As income level increases, the risk of disease decreases.

What factors lead to the formation of kidney stones?

Fluid intake: this is one of the most important factors. Reduced fluid intake increases the risk of kidney stones. There is no specific amount that prevents the disease. The season (a rise in the incidence of the disease is observed in summer), excessive sweating and metabolic state constitute an indication. It is recommended to always have a jug of water at hand. For example, if a person increases his water consumption from 1000 to 1500 ml, his risk of kidney stones is reduced by 80%.

Diet: Increased consumption of sugar or carbohydrates increases urinary calcium levels. Uric acid in high animal protein diets can increase the incidence of kidney stones. Excessive alcohol use causes increased urinary calcium levels and decreased urinary excretion of a protective citrate substance, which increases the risk of kidney stones.

Can a kidney stone reappear after its treatment?
The probability of a single or multiple recurrence is 10% within one year, 35% within 5 years, and 50% within 10 years. Recurrence is associated with certain risk factors:

• Onset of the disease at an early age (under 25 years)
• Frequent urinary tract infections
• Specific types of stones (infectious stones, uric acid/urate stones as in gout, brushite stones)
• Children and adolescents
• Genetic diseases (such as cystinuria, primary hyperoxaluria, renal tubular acidosis type 1, xanthine, and cystic fibrosis)
• Hyperparathyroidism (parathyroid gland)
• Intestinal diseases and previous gastrointestinal surgery (intestinal absorption disorders, previous gastrointestinal surgery, Crohn's disease, colitis, and some metabolic diseases)
• Family history of the disease
• Patients with only one kidney
• Large stone burdening on both sides
• Presence of stones after treatment
• Specific medications (excessive calcium and vitamin D intake, some diuretics, antacids, and some thyroid medications, etc.)
• Anatomical abnormalities of the kidney and urinary tract
• Lack for citrate in urine (citrate has the effect of preventing stone formation)
• Change in urine pH values (excessive rises and falls)

 

Are stones always the same kind?

Stones vary in shape, structural composition, hardness, and size. Calcium stones are the most common (82% of cases). 3/4 of these represent calcium oxalate, and 1/4 is calcium phosphate. Excessive amount of parathyroid hormone in the body, cancer or certain kidney diseases can lead to this type of stone. 7% of cases are infectious stones, which usually grow to huge kidney stones.

The decomposition of certain microorganisms in the urea in the urine releases an enzyme that makes urine alkaline and causes the stone to fall out. This occurs most often in women.

There is a 7% greater likelihood of uric acid stones especially in patients with a diet rich in meat, which forms stones passed in the urine. Gout and certain chemotherapies trigger the formation of this type of stone. They are not visible by X-ray but can be diagnosed by ultrasound or CT scan.

Cystic stones occur in cases of cystic fibrosis (1 - 3%). They occur very rarely but often recur. They can be caused by taking medications such as indinavir and sulfonamide. They are not visible on X-ray. Analysis of stones that have entered the urine is important for kidney stone diseases and potential cases. Analysis of the stone is one goal of surgery in order to determine the predisposition of recurrence, the subsequent treatment plan, and the identification of any hidden disease.

Anyone who has tried to pass a kidney stone has witnessed the fact that it can be very painful, even more so than childbirth. This pain only occurs only when the urinary tract is obstructed. Most cases of kidney stones can pass with or without any pain without medical help. Stones that cannot pass not only cause pain, but also carry a potential risk of infection, blood in the urine, kidney dysfunction and require appropriate treatment with a urologist. The following can be an early indication of kidney stones and certainly require the patient to visit a urologist.

Pain: Pain which is one of the most important signs of kidney stones occurs when the urinary tract is obstructed. Sudden or complete blockage causes severe pain. The reason for the pain is that the stone exerts pressure which grows in the rest of the urinary tract. Sometimes the pain, just as with labor pains, may be accompanied by nausea and vomiting. The pain is usually from the back when the stone obstructs the outlet of the kidney (the internal urinary duct between the kidney and the urinary bladder). As the stone passes downward, the location of the pain moves to the groin.

Nausea, vomiting, blood in the urine: another possible symptom is blood in the urine, which makes the urine take on a slightly pinkish hue. Cloudy, sludgy, and malodorous urine are also symptoms.

Infection: stones in the urinary tract are often accompanied by infection. Infection is manifested by fever, chills, and shivering. This condition is most common in cases where the infection affects the kidney itself.

Urinary disorders: possible signs are burning while urinating, frequent urination, prolonged feeling of the need to urinate and inability to pass urine completely. Stones that do not obstruct or only partially obstruct the urinary tract may pass without being felt and may become quite large without showing symptoms. Stones that are located in the kidney may not cause pain if they do not obstruct the flow of urine. They can cause pain that resembles mild muscle pain in the lumbar and back area. When the kidney is all in stones, there may not be any discomfort.

Some kidney stones are discovered accidentally, during a routine examination. But they are usually diagnosed by ultrasonography and urine tests, which are carried out after the onset of symptoms, such as blood in the urine or strong pain. Ultrasonography is not suitable for detecting stones in the ureter (the duct between the kidney and the urinary bladder) and a CT scan is required for definitive diagnosis. It is possible to assess the functionality of the kidney and the anatomy of the urinary tract using enhanced scanning.

Which factors should be considered when planning treatment of the kidney and urinary tract?

• The size of the stone
• The number of stones
• The structure
• The shape
• The location
• Symptoms or lack of symptoms
• The possibility of the stone falling out
• The presence of infection
• The presence of a blockage
• The presence of additional diseases
• Age
• Occupation
• Choice of treatment

 

Is it possible for the stones to pass by themselves?

The possibility for a stone to pass by itself depends on the size, shape, the number of stones and location of the stone(s) in the kidney and urinary tract. Smaller stones may exit the kidney and descend into the bladder, relatively painlessly, through the 4 mm wide internal urinary tract before being expelled through the urethra during urination. 85% of stones are small enough to pass quite easily, although painfully at times, and are expelled in the urine within 2-3 days. These stones are usually 4-5 mm in diameter. The chance of stones sized 6-7 mm to pass like this is small. The chance of a 5 mm stone to pass is 50%.

Does the stone cause pain while passing?

Sometimes patients experience severe pain when the stone descends. You should drink plenty of water (2-3 liters per day) and do physical exercises during this period. If the pain is tolerable, there is no distinguishable blood in the urine or infection, and the process has no significant impact on the kidney function, it is possible to wait for the stone to pass. There are treatments that make it easier for the stone to pass and limit the pain during this period. Kidney function should be monitored during this period.

When is it necessary to actively treat the disease or remove the stone from the body?

• If the pain persists after 3-4 weeks and the stone has not yet passed
• For stones 6-7 mm in diameter or larger
• The pain does not decrease enough
• With signs of obvious blockage or dilatation of the urethra tract or kidney
• Risk of infection
• If you have one kidney that is blocked
• In case of stones on both sides

Kidney stones can reach quite large sizes, if the stone does not cause blockage while growing, it can fill the entire kidney. These stones are called "staghorn" or "coralliform" stones because of their complex shapes. These stones require surgical removal. Patients suffering from severe pain are usually examined in the emergency room and given strong pain medications. However, before treatment, other possible causes must be eliminated. Apart from this, patients with kidney stones are given specific preventive medicines. If the type of stone has been specified and blood and urine tests have identified the underlying problem, treatment directed at the cause can be administered, with a medication that reduces the risk.

 

What are the treatment options for kidney stones?

In the past, the only option was with an open surgery. However, advancing technology has increased the possibilities of a closed surgery (endoscopic treatment). If a patient is in severe pain, the first thing to do is to reduce the pain and create comfort for the patient. Next, treatment is planned based on a detailed assessment of the stone(s).

Under what circumstances is intervention necessary?

Interventional treatment is planned regardless of the size of the stone, if it has not passed within 3-4 weeks, or if its size is established diagnostically and is 7-8 mm or larger. Stones that are located in the small cavities of the kidney called calyces do not obstruct the urinary tract and do not cause discomfort to the patient. They can be monitored for some time, but it is generally accepted that since these stones are the least dangerous to the patient, the least risky treatment is the most appropriate. Even if they do not bother the patient, stones that fill the entire kidney, or a large part of it, require surgical removal because they pose a risk of infection, severe kidney dysfunction, or cancer. It is vital that the kidney is completely free of stones after surgery.

How is the intervention method chosen?

Although similar externally, the small cavities (calyces) that collect urine before it passes forward along the urinary tract and the main basin (renal pelvis) can be very differently structured. Factors such as this are important in the choice of interventional treatment. Determining factors include patient-specific issues such as general condition, location of the stone(s), size, number, structure, degree of congestion, changes in the kidney, presence of infection, bleeding, clotting disorders, whether the patient has only one kidney, the patient's occupation, the patient's preoperative tolerance for discomfort and his or her expectations of treatment, and technical factors such as the surgeon's experience, available equipment, variety and sufficiency of instruments and supplies.

What is shock wave therapy and when can it be applied?

Until the 1980s, when open surgery was the only option, the recovery period for patients reached 4-6 weeks. In the 1980s, non-invasive extracorporeal shock wave lithotripsy (ESWL) was introduced, a form of treatment that is now a widely used method for breaking up or crushing kidney stones. It is an outpatient treatment that does not require hospital admission. The doctor and patient decide on this treatment based on the size and the location of the stone. The most important indications for success are the size, number, and location of the stone(s). Shockwave treatment is designed to break the stones into smaller fragments that can then pass on their own. Endoscopic treatment is more suitable for patients whose condition is not repairable with ESWL.

Shock waves inevitably pass through the fleshy part of the kidney (parenchyma) and there may be blood passing in the urine for the first few days after treatment. Therefore, medications that thin the blood are stopped a few days before treatment begins. After the first session, a detailed assessment is made as to whether the stone has been fragmented or partially fragmented, or whether a repeat session should be planned; treatment should be carried out within a reasonable period and with a reasonable number of sessions.

This treatment option is not recommended for pregnant women, patients with uncontrolled infection of the unitary tract, patients with difficult-to-control coagulation diseases, patients with an aneurysm in blood vessels near the stone, patients with skeletal abnormalities that make them difficult to position, and patients who are overly obese.

What endoscopic interventional methods are used in the treatment of kidney stones, how and when are they applied?

Endoscopic surgery is preferred in cases where the stone does not pass by itself and when shock wave treatment is not applicable. When treating a ureteral stone, a ureteroscope is passed through the urinary tract and the stone is reached, then it is broken up using a laser and removed from the body. Nowadays, stones up to 2 cm can be removed with closed - as this one is, endoscopic surgery. In this method, a very thin, flexible device whose tip is operated by the surgeon is used to break up the stone with a laser (flexible ureteroscopy F-URS); the stone is then removed from the body. Usually these operations, can be done in one day with an overnight stay in hospital.

What methods are used to remove larger stones?

Percutaneous nephrolithotomy (PCNL) is an ideal treatment method for removing stones in cases where shock wave therapy or ureteroscopy are not appropriate or when the stones are larger (1.5 - 2 cm and larger). A 1.5 cm incision is made on the side of the back that covers the kidney. A tunnel is then made, from the skin to the kidney, to create access for a telescope. The telescope is used to locate an existing stone and any small stones that may not be visible with radiography. The telescope has an internal canal that allows the passage of instruments that are used to break up the stone.

The main advantage of percutaneous nephrolithotomy is that these same instruments have the ability to suction and/or grip the stone fragments. Not only can a stone be taken for analysis, but usually the stones are cleared from the patient after such a procedure and therefore there is no need to worry about passing any stone fragments. If the stone is particularly large or complex in shape, more than one tunnel into the kidney may be needed to remove any stones present.

At the end of the procedure, a small tube is left to drain the kidney. Percutaneous nephrolithotomy usually requires a hospital stay of about 1 or 2 nights. X-rays may be taken after the procedure to check that all the stones have been removed and that the kidney is draining properly. If stone fragments are left, a second procedure may be recommended to remove them. The tube from the kidney is often removed at the end of the second procedure. It is normal to have some blood in the urine for a few days after a percutaneous nephrolithotomy. This procedure is suitable for any age group (including children) and any patients.

How often and under what circumstances is open surgery preferred?

Nowadays, open operations are very rare (1-5%) and are not performed except in exceptional circumstances. Open surgery may be considered if a pathology is found that indicates the need for open surgery, or in cases of severe structural renal disorders in which endoscopic intervention is considered risky. In rare cases of very large stones (over 5-6 cm), when the surgeon is not very experienced in endoscopic surgical techniques and does not wish to prolong the duration of surgery and anaesthesia, it may be decided to undertake open surgery.

A group of patients in whom open surgery may be necessary are obese patients. Open surgery may also be preferred in cases in which the stones cannot be broken up using shock waves and in which closed surgery is not applicable. Open surgery may also be considered when it is necessary to correct a kidney or the urinary tract, and when stones are being removed.

What problems can occur if kidney stones are left untreated?

If stones pass easily through the urine, usually no serious problems occur. If the blockage associated with a stone does not persist for a long period, permanent damage rarely remains. However, if the blockage continues unnoticed for a long period, an infection or permanent kidney damage may occur. In cases where stones occur frequently, over time, infections associated with the blockage, large stones and, in frequently operated patients, a change in the kidney's function can occur. 

Can kidney stones be prevented?

50% of patients with kidney stones suffer from some form of recurrence within 10 years. Some measures can be taken to reduce the risk of kidney stones. You should consume enough fluids (mainly water) to produce 1.5 - 2 litres of urine every day. There is an inverse relation between fluid intake and stone formation. Since stones are mainly composed of calcium, even reducing the consumption of calcium-rich foods has been found to prevent kidney stones. However, in rare cases (excessive intestinal absorption of calcium in the gut, patients who take high doses of calcium tablets) the risk is increased. The recommended daily calcium intake is 1000 mg. Foods fortified with vitamin D and calcium-based antacids should be avoided.

Foods of animal origin should not be overconsumed; they reduce urinary oxalate and citrate, which may increase uric acid. A balanced diet is recommended. Dietary fibre in the diet should be increased. Patients with oxalate stones should reduce their consumption of oxalate-rich foods. Vitamin C consumption can be reduced - it should not exceed 500-1000 mg. Spinach, cereals, cocoa, cola and excessive consumption of tea and nuts stimulate oxalate stone formation. Reduce salt in your diet.

Daily consumption of salt in quantities above 5 g increases the danger of calcium stones. Patients who have passed more than one stone, or who have had surgery because of it, should have blood tests and 24-hour urine tests for specific substances in the blood and urine that increase the risk of stone formation and should be tested for low levels of substances that prevent stone formation.

If possible, the stone or stone fragment should be analysed to determine what type of stone it is. It may be possible to prevent or stop certain types of stones from occurring. Some diuretics could be helpful to lower in urinary calcium excretion. If the urinary citrate level is low, citrate tablets or citrate-rich products, such as lemonade, would be helpful.

Patients with oxalate stones should consume pyridoxine foods (vitamin B6), which reduce oxalate. Certain medications that are taken orally can be effective in the prevention of uric acid stones. Excessive consumption of grapefruit juice can amplify stone formation. Orange juice can be beneficial as it is rich in citrate. Cranberry juice is not recommended. A rise in the level of magnesium in the urine may reduce stone formation.

Is it possible to dissolve the stones by taking medication orally?

Medicines that are taken by mouth can be used to dissolve uric acid stones. Infectious stones can be dissolved using a tube inserted into the kidney. Once it enters the kidney, only percutaneous nephrolithotomy PCNL can clean it of the stones.

Is urine acidity a factor in stone formation?

Most stones occur when the urine is alkaline. Therefore, increasing the acidity of the urine is a possible preventive measure. In cases of uric acid stones, taking steps towards making the urine more alkaline would be beneficial.