Renal lithiasis: causes, types, symptoms and treatments

• Kidney stones are a very common pathology, with approximately 5-12% of the population suffering from some symptoms before the age of 70.
• Urinary calculi are concentrations of matter that form in the kidneys. When they reach the bladder and urinary tract, they cause pain crises.
• One of the treatments is lithotripsy, which consists of pulverising the stones by different means: laser, tweezers or ultrasound.

Renal lithiasis, also called urolithiasis or nephrolithiasis, is the presence in the urinary tract (ureters or bladder) or in the kidneys of stones formed as a result of chemical substances in the urine. 

The most common factors that promote stone formation are:

• High concentration of substances in the urine such as calcium phosphate, calcium oxalate or uric acid, present in foods such as red meat, seafood, alcohol, etc.
• Urine stasis, i.e. the urine circulation stops.
• Urine infections, caused by the appearance of bacteria in the urinary tract, most stones being formed by calcium oxalate, and less frequently by uric acid, calcium phosphate, struvite and cystine.
• Imbalances between factors favouring and inhibiting the concentration of substances in the urine.

Kidney stones are composed of normal substances in the urine, which have concentrated and solidified into fragments.

Renal lithiasis is not always present in the form of a concentration called a stone; in some cases, they can also be grit. However, we explain how stones usually form in the following stages:

Phases of formation and growth of kidney stones

As we mentioned, lithiasis necessarily goes through a succession of several stages until the stone forms and grows progressively. These stages are:

1. Over-saturation of urine: Urine is a solution of various salts that are usually in different concentrations. These concentrations or solutes can join with more solutes, leading to a state of saturation, resulting in crystallisation of the substances.
2. Crystalline germination: crystals increase in size and may break into smaller pieces.
3. Crystal growth: the crystals continue to increase in size of the particles formed, either by individual growth or by aggregation of the crystals with each other.
4. Stone retention: finally, stones that have not been expelled are retained either in the walls of the kidney, in the renal tubule or in the urinary tract.

This ailment can be the result of a combination of different causes, the most common of which are described below.

The main factor in the development of kidney stones is a lack of fluids. Although there are discrepancies, there is no reliable evidence that the type of fluid ingested affects stone formation. Other causes associated with the development of kidney stones include:

• Excessive consumption of products containing vitamin C increases renal secretion of oxalate and increases the risk of calcium stones.
• Genetic inheritance. People who have a family history of kidney stones or who have already suffered from them themselves, it is important to monitor both the amount of urine they produce, at least two litres a day, and the colour and odour of their urine. A faint odour and light colour implies proper hydration.
• Urinary tract problems: the formation of urinary stones is usually due to an obstruction in the passage of urine or in the case of a urinary tract infection.
• Dietary excesses: mainly diets rich in salts, sugars and proteins are risk factors for the development of kidney stones, especially in people who have already suffered from calcium concentrations. Although calcium is the main element of kidney stones, it is not to be dispensed with. The only drawback is the use of calcium supplements, as they are a potential cause of kidney stones.
• Other factors: obesity in people over 40 is a risk factor. The same applies to hypertension, diabetes and gout. Kidney stones are more common in men than in women.

Kidney stones form when the urine is saturated with salts or because the urine lacks natural inhibitors.

In short, stones are the result of the formation and clustering of crystals in saturated urine, caused by physical phenomena such as a high concentration of salts in the urine and an imbalance of factors that inhibit and promote the concentration of the elements present in the urine.

It is therefore necessary to monitor the above factors to prevent the formation of kidney stones and thus avoid aggravation of renal lithiasis.

There are different types of kidney stones, whose classification is mainly due to the substances of which they are composed:

• Calcium oxalate and apatite stones: Calcium stones are the most frequent. Both compounds (oxalate and calcium) are natural chemicals and are eliminated in the urine. They form from processes such as drinking insufficient fluids or consuming calcium-rich foods. It is usually suffered by men in their 20s and 30s.
• Calcium phosphate stones: This type is also quite common, as phosphate is a common compound in urine and in the body. It is a mixture of calcium oxalate and calcium phosphate. It usually occurs in patients with an excess consumption of phosphate-rich products such as dairy products.
• Uric acid stones: This type of stone is formed from a nitrogenous compound found in the urine. They usually appear in 10% of cases. Uric acid is a waste product resulting from the metabolism of certain foods, such as red meat or beverages such as alcohol. It should be noted that these stones cannot be seen on X-rays, so it is necessary to use contrast tests or ultrasound scans.
• Struvite stones: Struvite is a compound of ammonium, magnesium and acid with phosphorus. It is also known as an infection stone, as it forms when the urine is infected. Special care must be taken with this type of stone, as it is the most dangerous type, due to its large growth and coexistence with a permanent infection that can unbalance the correct functioning of the affected kidney.
• Cystine stones: Cystine stones are caused by the breakdown of proteins. They are formed in people suffering from cystinuria, a hereditary disorder that affects women and men equally. It should be noted that the size of this type of stone can vary from very small to a diameter of 2.5 cm.

Kidney stones can be differentiated by their constituent substances: calcium, phosphate, oxalate and purines.

Renal lithiasis can have different symptoms, depending on factors such as size, composition and location within the urinary tract, i.e. if the material is found inside the kidney or urinary tract, it is called renal lithiasis. 

On the other hand, if the stone is in the ureter, it is called ureteral lithiasis. Finally, there is also the possibility of bladder lithiasis, which occurs when the stones are found in the bladder.

Renal lithiasis presents different symptoms depending on the size, composition and location of the kidney stone.

The most common problem caused by kidney stones is called nephritic colic, which occurs when a stone causes blockage of the outflow of urine from the kidney, causing intense pain in the kidney area, extending to the abdomen and genitals. This pain is often accompanied by abdominal swelling, nausea and vomiting.

Lower back pain is also usually a symptom of kidney stones, although it is often confused with bone or muscle pain.

Other symptoms typical of this condition include:

• Abnormal urine colour: Abnormally coloured urine may be cloudy, dark or pink. This condition may be due to bacterial infections, excess bilirubin in the urine, injury to the kidneys or urinary tract.
• Blood in the urine: This may be visible to the naked eye or, conversely, can only be seen by microscopic examination. This problem appears due to the small wounds produced by the stone as it passes through the affected organs. Sometimes it is the only manifestation.
• The need to go to the toilet more frequently than normal: This situation may be due to different problems such as urinary tract infection, inflammation and infection of the urethra, prostatic enlargement in men and vaginitis (inflammation or discharge from the vulva and vagina).

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In addition to specific dietary guidelines and appropriate medical treatment, there are other useful general guidelines that are usually sufficient to prevent stone formation. These general guidelines are:

• Increase daily fluid intake, drinking about 2 litres of water per day helps to maintain a good dissolution of urinary salts. This will cause urine to circulate rapidly, which is essential for proper control and prevention of urinary tract infection.
• Limit intake of foods that have urinary stone components, substituting diuretic herbs such as parsley, nettle and dandelion.
• Do not eat excessive meat, about two portions a day.
• Regulate the consumption of dairy products. Dairy consumption is necessary to maintain adequate bone development, but the excess is discarded by the bone and eliminated in the urine, which can lead to saturation that favours the development of stones.
• Controlling urinary tract infection is a very important preventive measure, especially in the case of women. It is recommended: avoid constipation, do not hold back urine, avoid a sedentary lifestyle and empty the bladder immediately before or after sexual intercourse.

The best way to prevent kidney stones is to follow a low-calorie, low-salt diet, limiting animal proteins, sugars and alcohol.

However, this information is of a general nature, so its effectiveness will always depend on the characteristics of each patient and the specific indications of a health professional.

The diagnosis made to determine the presence of one or more kidney stones requires prior evidence such as the expulsion of a stone and the sum of several symptoms such as those mentioned above. Likewise, after consulting a urology specialist, various tests will be required to determine the presence of kidney stones.

A number of tests and examinations may be needed to diagnose kidney stones.

The most common tests are:

• Kidney function tests are common laboratory tests used to evaluate kidney function. These tests include: BUN (blood urea nitrogen), blood creatine, creatinine clearance and urine creatinine.
• Blood tests, the blood contains red blood cells, white blood cells and platelets. The test measures the number and type of cells found in the blood.
• Urinalysis is often done to check for urinary tract infection, kidney problems or diabetes. It is also used to monitor some medical conditions and treatments.
• CT scan of the abdomen, this test uses x-rays to create cross-sectional images of the abdominal area.
• X-ray of the abdomen, medical images taken to look at organs and structures in the abdomen. Organs include the arm, stomach and intestines. When this test is done to look at the bladder and kidney structures, it is called a KUB (kidneys, ureters, and bladder) x-ray.
• MRI of the abdomen and kidney is a test that uses powerful magnets and radio waves to create images. The waves create images of the inside of the abdominal area. No radiation is used.
• Intravenous and retrograde pyelography is a special examination of the kidneys, bladder and ureters (the tubes that carry urine from the kidneys to the bladder). Radiation (x-rays) is used.
• Ultrasound of the kidney is a test that consists of an examination by means of ultrasound emission. In urology, it allows the study of various organs of the genito-urinary system such as the prostate, bladder, kidney and testicles.

Kidney stones that do not cause symptoms can be diagnosed during a routine urinalysis.

Urological specialists are responsible for determining the presence of kidney stones based on the analysis of clinical symptoms and the results of the urinalysis. Other factors such as the location of the stone within the urinary tract, size and impact of the stone are assessed with renal ultrasound, abdominal X-rays and intravenous contrast urography.

Regarding the detection of stone composition, this is done by means of specific tests.

However, not all tests are necessary to diagnose the presence of kidney stones. It is usually sufficient to perform some of them to be certain of the appearance of matter in the kidneys.

Based on the diagnosis, specialists will be able to determine the treatment best suited to each case and thus provide the most effective solution for the patient. The following is a breakdown of the most common treatments.

When it comes to establishing a treatment and after diagnosis, specialists take into account above all the size and position of the kidney stone. Therefore, there are two main types of treatment:

Conservative or pharmacological treatment

In cases where the stones are small enough, experts do not recommend any surgical treatment. The condition can be easily eliminated through urination. In case the stones cause the patient any pain, specialists resort to prescribing medication to help the stones to be eliminated and expelled in the urine.

A high percentage of stones present in the ureter are spontaneously expelled within several weeks, depending on their size and position.

Prognosis after conservative treatment

As the stones are small or easily removed by medication, the chances of success are high. However, it should not be forgotten that this type of condition is usually genetic and recurrence is possible. Therefore, it is necessary to take the preventive measures indicated by the specialists, mainly the care of the diet and fluid intake.

Surgical treatment

In other cases, when the stones are too large, surgical treatment is used to solve the affliction. There are different types of surgical interventions.

• Extracorporeal shock wave lithotripsy (ESWL): this involves the fragmentation of stones by means of the extracorporeal application of energy from shock waves produced by a generator (electrohydraulic, electromagnetic or piezoelectric). This procedure is performed under analgesia and sedation of the patient.
• Percutaneous nephrolithotomy: in this case, the stones are removed using an endoscope inserted directly into the renal pelvis and calyces.
• Ureterorenoscopic lithotripsy: this procedure is performed with an endoscope inserted through the urethra and bladder into the ureter.
• Stone resection: this is surgery in cases where the stone is of a size or shape that prevents it from passing and blocks the flow of urine, or when it is causing damage to the kidney or urinary tract. The process consists of removing the part of the kidney affected by the stones, exceptionally the kidney is removed completely.
• Holmium laser endoureteral lithotripsy: this is the most advisable procedure, as it involves the removal of renal bodies without making any kind of incision in the patient. The Holmium laser gets rid of most of the residual material in the kidney. Unlike extracorporeal lithotripsy, Holmium laser lithotripsy allows most of the residual material to be removed during the procedure itself.

Holmium laser lithotripsy is the most recommended procedure for the removal of kidney stones, as it allows all the material to be removed in a single operation.

Prognosis after surgical treatment

In most cases, kidney stone surgery leads to total elimination of symptoms.

In rare cases, however, stones may recur. This is usually due to genetics or in case of not having followed the relevant medical recommendations.

Therefore, specialist advice to avoid possible urinary tract infections or stone recurrence should be taken seriously, including eating a balanced diet and caring for wounds until they are completely healed.

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Holmium laser lithotripsy surgery (kidney stones) is performed when the Urology specialist determines, during the surgical assessment consultation, the viability of the treatment to eliminate the kidney stones.

In addition, before the operation for kidney stones, it will be necessary to carry out a complete preoperative examination to determine your general state of health as well as to know in detail the state of the kidney stones causing the problem.

This preoperative consists of tests such as:

• Electrocardiogram: to find out the health of the patient's heart.
• Blood tests: to find out if there is any infection or if there is any associated problem that could compromise the surgery.
• Chest x-ray (if requested by the doctor): this lets the doctor know if there is a risk of infection or if there may be a problem with the patient's rib cage.

Once the tests have been carried out and you have been given the go-ahead for the operation, the day of admission for the procedure will be determined.

On the day of the operation and once in the hospital, after being admitted you will be accompanied to get ready for the operation, you will be asked to dress in your surgical clothes and you will be taken to the pre-surgical room. 

When the time comes, you will meet the urologist and his team again in the operating theatre where you will be shown how to position yourself and the operation will begin:

1. The urologist will first dilate the urethra to allow access to the ureteroscope, which is a small tube with a camera and a light at the end that allows the surgeon to see inside the urinary tract through a monitor.
2. The ureteroscope also allows the Holmium laser fibre to be passed through the urethra to the kidney stone site so that it can destroy the stone. This is made possible by the flexibility of the ureteroscope.
3. Once in the bladder, the surgeon fills it with a saline solution that improves its visibility and allows easier access to the ureter.
4. When the surgeon gains access to the kidney or the area where the stone is located, it will be destroyed using any of the three common techniques, which are direct fragmentation, the most commonly used for small stones in complex areas, multiple drilling, which consists of drilling a large number of holes in the stone to facilitate fragmentation and extraction, and ablation of a superficial cavity, which consists of drilling a large hole in the stone to fragment it into a few pieces.
5. After removal, the surgeon will check that everything has come out correctly and place a probe to facilitate the removal of the remaining debris.
6. All the material is then removed and the patient is awakened.

The duration of Holmium laser lithotripsy surgery is about 1 hour.

Once the kidney stone surgery is over, you will be transferred to the resuscitation room where you will finish recovering from the anaesthesia and your vital signs will be restored.

If you want to have kidney stone surgery to remove the kidney stones that make your life impossible, remember that you can request a free surgical assessment consultation with our specialists to meet them, review your case and decide together the best option for your medical problem. 

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