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Urine contains different salts. If the concentration of salt becomes too high, for example, if you have been drinking too little, crystals can be formed. They can then grow into forming so-called kidney stones. If the stones are really small, they are flushed out with urine and give no hassles. On the other hand, if the stones are larger, they can get caught in the urethra and stop urine flow. Stones can also remain in the kidney pelvis, which is the first part of the urethra, and there are other disorders such as recurring urinary tract infections, aches or blood in urine.
What are kidney stones?
Kidney stones are the result of a disease that affects the urinary system called with the medical terms kidney lithiasis, nephrolithiasis or kidney stones. Kidney stones are solid agglomerates that are formed in the urinary tract as a deposit of substances that our body, in some particular conditions, cannot dispose of. Often kidney stones are asymptomatic, and for this reason it is difficult to notice their presence until the moment when some factors determine the onset of painful access called renal colic.
Kidney stones are widespread and also due to the fact that it is difficult to notice their presence and it is crucial to understand what they are, how they are formed, how to prevent them even through a balanced diet, which symptoms should make us suspect that they are at risk or having developed them and how to treat them.
Kidney stones are most common between the ages of 20 and 50, and often affect men than women. Every fifth to tenth one gets the disease sometime during life. You can have a hereditary risk of getting kidney stones easier.
Kidney stones are presented as pebbles of various shapes, which were formed in the beginning as tiny clusters of crystals and which progressively expanded to attract new molecules. In some cases their size is such as to occupy the entire renal cavity and to compromise renal function. In other cases, the calculation, which has remained small in size, moves along the urinary tract, causing very painful contractions and frictions that give rise to renal colic.
A stone that prevents urine from freely passing down to the bladder causes the kidney pelvis to become strained. The pressure increases and it starts to hurt. If it lasts for a long time, pressure increase can damage the kidney. If you have a urinary tract infection at the same time, there may be a risk of sepsis, also called blood poisoning. Everyone who has had kidney stones gets a new stone within ten years. You can have an intense pain that feels worse in the side or back of the side where the stone is sitting. The pain can radiate against the abdomen or groin.
There distinguish two large groups of types of kidney stones by shape and size:
- Mold stones: these are formations that have completely or partially occupied the renal cavity, tracing its ramifications and morphological complexity as in a mold, hence its name. They are also called coralliformic stones, because their shape is reminiscent of coral. These are very difficult stones.
- Non-mold stones: as is easy to guess, are stones that do not reproduce the shape of the renal cavities. Normally they are small in size, but can in some cases reach significant dimensions over 1.5 – 2 cm. Crystallization can give rise to very different shapes: for example oval, jagged stones in the form of elk horns.
When kidney stones, following the flow of urine or bodily stresses, come out of the kidney and move along the urinary tract, we talk about urethral calculi and bladder stones.
Urethral calculi are crystallizations that have reached the urethra. They can be still or slow moving. The process can be painless or give rise to renal colic. In addition urethral calculi can also be at the origin of urinary flow obstructions (hydronephrosis) and its subsequent stagnation in the urethral tract, called urethrohydronephrosis.
Bladder stones instead are crystalline agglomerates in the bladder. These may be urethral stones which, after running the urethra, reach the bladder, or crystallizations formed in the bladder due to other pathologies such as prostatic hypertrophy (benign prostatic hyperplasia) or the neurological bladder (neurogenic bladder). If their size allows it at this point kidney stones are expelled spontaneously with the urine.
In addition to the shape and location, kidney stones are also classified according to their chemical composition and the pathology or clinical picture that caused them.
In the first case the classification of kidney stones is made on the basis of the main substance that makes up the calculation and includes 7 types:
- Calculations from calcium oxalate;
- Calculations of uric acid;
- Calculations of calcium phosphate;
- Cystine stones;
- Struvite stones;
- Calculations from drugs;
- Calculations of 2-8 dihydroxyadenin (DHA).
In the second case we talk about classification by pathogenesis that distinguishes three types of stones:
- Primitive or idiopathic forms: these are stones that are not due to external causes, such as feeding, bacteria or taking drugs.
- From morphological changes: in this case kidney stones are the result of a modification of the renal apparatus or its functioning.
- Secondary forms: that arise as a consequence of other pathologies, to the assumption of particular types of drugs or in specific pathological pictures.
How do kidney stones form?
the concentration of the salts becomes too high or if the balance between the salts is rubbed, the salt can be precipitated into crystals and stones formed. The concentration of salts becomes too high either because more salt is excreted in urine or that urine becomes too concentrated. This can happen if you do not drink enough or if you lose large amounts of fluid, for example in diarrhea.
The most common type of kidney stone contains calcium (calcium salt). Too much and too little calcium in the diet has been shown to increase the risk of kidney stones. The best advice is therefore to eat a varied diet and to drink a little extra if you know that you have the risk of forming kidney stones.
Rare times, kidney stones cause the thyroid gland to form too much of a hormone that regulates the amount of calcium and phosphate in blood and urine. This causes too much calcium in the blood and urine. Urine may contain too much of substances other than calcium. This includes uric acid, oxalate and cystin, all of which can form stones. Kidney stones also form more easily if the acidity of urine has changed. The change may be due to congenital damage or caused by an infection.
In general, it is possible to state that kidney stones are the product of the precipitation of substances that are not soluble in urinary environments, for example mineral salts (such as calcium) or organic compounds (such as uric acid) which, due to specific risk factors they increase and aggregate in the kidneys. The scientific community believes that kidney stones are formed due to three pathophysiological processes that may be present in various degrees, intensities and combinations.
The over-saturation is one of the determining factors for the creation of kidney stones and occurs when in our body a specific salt saturates the environment in which it is located, in this case the urinary, and alters the normal physiological processes.
Over-saturation gives rise to pathological situations affecting the urinary system, especially when it encounters a favorable urinary environment: when the urinary pH falls below a certain threshold (acid pH), the physiological base acid balance disappears and a fertile soil is created so that the salts precipitate and aggregate giving rise to the crystals (crystallization). At this stage we are not yet in the presence of kidney stones, but of crystals. If the conditions of the urinary environment remain altered, for example due to the prolonged risk factor anomalies, new crystals and / or other molecules are bound to the crystals, giving rise to the second stage of homogeneous enucleation. At this stage the crystal grows larger and progressively grows into a calculation.
In some cases precipitating and agglomerating to the crystals formed by the supersaturation are not only salts but also other substances, particularly cellular debris, are added. Cellular debris, which make up what is called urinary sediment, is a collection of organic waste that is eliminated in the urine. These include the crystals themselves, leucocytes, epithelial cells produced by the excretion of the urinary tract, erythrocytes, bacteria, parasites, urinary cylinders. In a healthy subject urinary debris is absent or very scarce, in particular conditions instead their presence increases resulting in a second factor in the formation of kidney stones. The urinary cylinders in particular, are protein precipitations that are formed on a base, called matrix, of mucoproteins (hyaline cylinder). For this reason this type of factor is also called a mucoprotein matrix.
The protein matrix, or hyaline cylinder, is formed in the presence of poor hydration, acidic pH and poor flow of urine. These molecules, the cellular debris and the mucoprotein matrixes, precipitating in a favorable environment, bind to the crystals and are the source of calculi composed of several substances. In this case, therefore, we speak of a heterogeneous enucleation. Furthermore, the presence of bacteria and parasites in an already critical setting may contribute to the complication of the clinical picture and the onset of further pathologies or particular types of calculi such as struvite stones due to Proteus infections.
A third element contributing to the formation of kidney stones is the incorrect metabolism of so-called lithiasis inhibitors. In fact, in a healthy organism, some substances are naturally present, such as potassium citrate and magnesium citrate, which prevent the formation of precipitation, crystallization and aggregations. In some physiological conditions, such as in the presence of infections or acidosis, these substances are in poor and inadequate concentration. In this way the organism is exposed to the formation of kidney stones.
Renal stones form stones that can follow urine into the urethra. There they can prevent urine flow and cause severe pain. If you get a kidney attack, it’s common for you to get more attacks later in life as well. Usually the kidney is not damaged, but if the stone prevents urine flow and increases the pressure in the urinary tract for two, three weeks, the kidney can damage.
Risk factors and related diseases
Clinical research has verified that you are more exposed to the risk of developing kidney stones, and to recurrences and complications, in the presence of certain diseases and certain risk factors.
Then there are pathologies that clinical research has put in close correlation with the onset of kidney stones.
These are diseases that can predispose to the formation of kidney stones:
- Metabolic syndrome;
- Cardio-vascular pathology.
The relationship between nephrolithiasis and these diseases can be configured in three ways:
- Causal. The relationship is direct. The pathology causes the appearance of kidney stones and represents the main cause. This happens for example in the case of: hypercalciuria and consequent osteoporosis; hypocalcic diet and consequent osteoporosis.
- Random. The relationship is indirect but in any case connected. This can be used in particularly serious cases with a high metabolic impact of the pathologies associated with nephrolithiasis.
- Association. When the same metabolic abnormalities cause both the related pathology and the calculosis.
Kidney stone symptoms
Anyone who has expelled a calculation knows that he does not want to repeat the experience. Sharp and irregularly shaped crystals, following the same pathway of the urinary tract through which the urine is eliminated, pass through a delicate tube (the urethra) that connects the kidney to the bladder and then pass outside through the urethra. If small fragments can be ejected without discomfort, a larger calculation can cause one of the strongest pains a human being can experience. However, during the developmental stages, kidney stones are very often asymptomatic and we realize that we have developed stones.
Man has two kidneys that lie above the waist on either side of the spine. The kidneys have curved shape and are 10-12 centimeters long. The part of the kidney that bends into is called the kidney gate and here the ureter enters the kidney. The urethra’s first part is shaped like a funnel and is called the kidney pelvis. In the kidney port there are also blood vessels that go to and from the kidney.
The kidneys and urinary tract are needed for the body to purify the blood and dispose of residues from metabolism. Every day, the kidneys form 1.5-2 liters of urine which consists mostly of water. The remainder is various residues such as urea and gall dyes, but also foreign substances that have entered the body, such as certain drugs. The urine is transported through the ureters, temporarily accumulates in the bladder and leaves the body through the urethra. The kidneys regulate urine volume, salinity and acidity. The amount of urine that is formed depends, inter alia, on the amount of fluid present in the body.
At the beginning, kidney stones are small like sand grains and easily follow urine out of the body. Larger stones can get caught, either in the kidney pelvis or in the urethra. The stones can be several centimeters large and fill the entire kidney pelvis.
When the normal flow of urine from the kidneys is blocked by one or more stones, the kidney pelvis is stretched out. Then it hurts, because the kidneys are surrounded by a tight capsule that does not bring along. The kidney may eventually stop working because the tissue can not withstand high pressure for a long time. The urethra blocked by a stone is tensioned. Constrictions in the ureter’s walls try to push urine further, but when it does not get hurt you can get hurt. That is why the pain often comes in intervals.
Kidney attacks often come back. If you have ever suffered, you may experience recurrent pain attacks. Kidney stones do not have to be a problem. In such cases, the stones are detected more by chance if you go through an X-ray or ultrasound examination for other reasons.
Examinations and diagnosis for kidney stones
Heavy pain without obvious, natural explanation and that does not pass by itself should always be taken seriously. You can usually expel smaller stones without getting caught. Those kidney stones do not cause much harm. Larger stones stick more easily, which can cause kidney damage if urine flow is blocked for two, three weeks. The risk of persistent kidney damage increases if you have a urinary tract infection at the same time.
At the doctor’s you will be told about their inconvenience, how long they have been and how it feels. It is important to describe the inconvenience as thoroughly as possible. The doctor also examines the stomach by feeling and listening to it. If the doctor easily strikes his knuckled fist in which the kidneys lie, you will feel very sore on the side where the kidney stone is located.
You will be asked to leave a blood sample showing how the kidneys work and how much calcium is present in the blood and urine. There is no blood sample that specifically shows that you have kidney stones.
To confirm the suspicion that it is kidney stones, you are X-rayed. It is investigated with computerized layer X-ray, so-called computer tomography. The survey shows if there are any stones. You can also go through a contrast ray, so-called urography. The survey shows whether there are rocks and if the kidney has damaged them.
Kidney stones, in all their forms, can be managed effectively, both from the point of view of surgical procedures and from that of medical therapy. However, it may be the symptom of underlying disease, of renal origin or, more generally, metabolic. A metabolic study should always be performed to understand what has changed that balance between inhibitors and calculosis promoters.
A good practice that is often recommended by nephrologists is to review family history and check for cases of calculosis or associated diseases. Furthermore, the accurate analysis of dietary habits can provide useful indications to determine if feeding and fluid intake is the basis of the disease.
Alongside these, physicians normally make use of objective examinations, laboratory analyzes (chemical analysis on stones, blood chemistry tests, urine collection in 24 hours, urine fasting) and diagnostic imaging (ultrasound and radiology BDM).
If it does not hurt or if the pain develops gradually over a long period of time, it may be more appropriate to contact a doctor at the health center. If necessary, the doctor will write a specialist to a hospital or a specialist’s reception. The rules for referral vary between county councils. There are also private specialists whom you can contact yourself without a referral. If you feel uncertain you can call the healthcare counsel first for advice. The ongoing investigation usually takes place where you sought care, either at the health center or at the hospital of the emergency department. If the stone is so small that the doctor expects to be able to pee it himself, the same doctor can follow up the treatment and, if necessary, renew prescription for analgesic medication.
Reduce the trouble yourself If you have had kidney problems earlier and recognize the symptoms, you can relieve the trouble yourself. This can be done by means of analgesics that have been prescribed by their doctor or with prescription medicines. Sometimes it may be nice to put something warm on your stomach. If the inconvenience is over, you do not need to seek care. If, on the other hand, you fail to get rid of the pain by means of analgesic medication, you should seek care again. If you get rid of your stone, do not drink extra fluid to rinse out the stone, as the fluid presses and causes you more pain.
Neartitis is primarily treated with analgesic drugs, either as a tablet, pill or syringe. Often, anti-inflammatory drugs are used in the group cox inhibitors, also called NSAIDs, such as Diclofenac or Voltaren. Sometimes stronger, morphine-like medications are needed. If you do not get pain free despite treatment you need to be hospitalized. If you have an infection in the kidney you get antibiotics. After some time you will be called to your doctor for follow-up control. At the doctor’s visit you can leave urine samples and do a renal function test. In addition, the doctor will take a position if further X-ray examinations are required.
Diet and proper nutrition
Diet is important but you have to be careful not to fall into the clichés and reiterate the importance to health and effective care of kidney stones to avoid fad diets. It is good to know that nutrition has a direct effect on the composition of the urine and consequently on the risk of each individual to develop kidney stones.
The diet can in fact be used to reduce the risk of forming stones, however since even with the same diet the metabolism of each individual can lead to very different results it is essential that each diet be properly customized, preferably after a complete and metabolic study.
There are many common places on the effect of diet on calculosis, the most dangerous always considers appropriate a reduction of calcium intake of food in those suffering from calcic calculosis. This is in most cases not only useless but capable of aggravating the situation irremediably. To help with nutrition, it is first necessary to find out what kind of stones you are suffering from and for what reasons. The specialist will then be able to compose the best diet.
Kidney stone treatments and care
If you have had kidney problems earlier and recognize the symptoms, one can try to relieve the pain of prescription pain medication. If it does not help or if you get a fever you should seek care. Small stones, less than five millimeters, often come out of their own after a while when you kiss. Most often, an X-ray is made when looking for care and then another within a few weeks to see that the stone is gone. If the stone does not come out of its own, it must be treated.
The most common thing is that you get so-called shockwave treatment that is available in some hospitals. This means that the stone is crushed by means of an apparatus that produces pressure waves. After that you can usually pee out the stone remains. If the stone cannot be broken, it usually needs to be treated otherwise, with so-called titthal surgery or with laser.
It is essential to point out that today kidney stones can be cured and especially prevented. In the face of a correct diagnosis and an appropriate therapy setting, kidney stones can be solved effectively.
Often the first treatments are aimed at treating the symptomatic cases: renal colic. What unites most of kidney stones is the impossibility of being dissolved by medical therapy alone. For this reason specialists usually resort to therapy with inhibitors, where the composition of the calculation allows it.
Among the inhibitors of the calculosis that are present in the urine there is one, the citrate that has, from the clinical point of view, of enormous advantage especially in the different cases of calcium and oxalate stones, and effective in almost all forms of calculosis.
Citrate is easily and accurately controlled, both from the point of view of administration and the evaluation of its effects.
1. reduces supersaturation of calcium oxalate and calcium phosphate by binding calcium in a soluble (complex) form;
2. prevents the aggregation of calcium oxalate induced by uric acid;
3. inhibits the aggregation of further salts and the growth of the calculation;
4. increases the solubility of uric acid and cystine to dissolve an already present calculation;
5. delays the aggregation of struvite stones, which are infected stones.
If the kidney stone is large, it must be removed. The most common treatment means that the stone is crushed by means of shock absorption, so-called ESVL. The equipment used for the stone crushing is not available in all hospitals, so you may need a referral to a larger hospital. To find the stone, X-ray or ultrasound is used. The actual treatment with shock waves takes about an hour and usually does not hurt much. You usually get a little painful and soothing medicine before treatment.
Afterwards you can excrete the crushed stone chips with urine. It can hurt quite a bit and you can then get pain relieving medicine. The treatment is outpatient, which means that you can go home the same day. Stone crusher is a safe treatment method and it is rare for serious effects of treatment. It is common for you to have blood in your urine a few days after treatment. Often, a couple of treatments are required for the stone to be crushed to such small fragments that they can pass the urethra.
About half of those who have had kidney stones are affected again within ten years. To prevent kidney stones, drink a lot of fluid, at least two liters a day. Then urine becomes more diluted and the risk of crystals is reduced. Prevention of drug treatment can also be sought after a specialist has been examined.
Surgical therapy for kidney stones
Sometimes the stone’s location makes it difficult to access it with shockwave treatment. It can also be so great that crushing is inappropriate. Then it may be necessary to remove the stone instead. The operation is almost always a so-called titthal surgery, when a tubular instrument is inserted through the skin or urethral mouth. Through the instrument the stone is crushed either by laser or ultrasound, and then the fragments can be sucked or picked up with special tools.
Extracorporeal shock wave lithotripsy (ESWL)
Extracorporeal lithotripsy is a non-invasive technique that aims to disintegrate urinary stones into small fragments that can then be expelled spontaneously with urine. Introduced in 1981, it is still one of the major therapeutic revolutions in the urology field.
PCNL represents the method of choice in the treatment of kidney stones with a diameter of more than 2 cm and of calculosis in the mold.
Ureteroscopy, possibly supplemented by the vision of the renal cavities (ureterorenoscopy) consists in the introduction by transurethral retrograde or, more rarely, percutaneously anterograde, of the ureteroscope in order to explore the excretory way and to allow, at the same time, the maneuvers necessary for the fragmentation and passing of kidney stones.
The most common indications are the complex calculus or the size of the calculation, the renal functional exclusion, the failure of other less invasive methods (SWL, PCNL), the coexistence of anatomical malformations (infundibular stenosis, calculus in calicous diverticulum especially if anterior, stenosis of the concomitant urethral joint, stricture of the urethral), obesity or other co-morbidities, the need for concomitant surgery, patient choice.
Endoscopic therapy of bladder calculosis
Since the pathogenesis of bladder stones is often due to cervico-urethral obstruction, endoscopic therapy is the ‘gold standard’ for both basic obstructive pathology and bladder stones.
Laparoscopy and retroperitoneoscopy
Laparoscopy, or celioscopy, is a surgical method that involves performing surgical procedures by making accesses in the abdominal cavity (transperitoneal) or in the retroperitoneum.
Renal colic (kidney stones) during pregnancy
10% of the world’s population is affected by renal colic during their lifetime. For some unfortunate women, kidney stones can occur during pregnancy. Pregnancy is a complex physiological state whose changes promote the formation of kidney stones, such as increased calcium in the urine and reduced peristalsis (movement) of the urinary tract.
When a woman has kidney stones during pregnancy it is more complex. This complexity is given by a limitation of undergoing x-rays and other treatments that may harm the fetus. Ultrasonography is the safest and most reliable test for both the fetus and the mother. However, other tests such as magnetic resonance or positron at a low rate can be performed depending on the severity of the clinical picture and the trimester of pregnancy. To confirm the diagnosis, the patient must be evaluated by a urologist, preferably in an emergency room or in a hospital ward.
The speed of spontaneous expulsion of stones during pregnancy is high. If there is a clinical complication such as acute pyelonephritis and / or urinary tract blockage, the urologist must act urgently because it increases the risk of premature delivery.
How to treat kidney stones in pregnancy
To eliminate the obstruction in the second trimester of pregnancy, it is possible to perform a uretheroscopy with extraction of gallstones, if the patient allows it. In some circumstances, the insertion of a urethral catheter to eliminate the obstruction is the best option, for temporary treatment, until the pregnancy is resolved.
There are other types of treatments that are contraindicated in pregnancy, such as extracorporeal lithotripsy or percutaneous nephrolithotomy. In conclusion, renal colic secondary to nephrolithiasis during pregnancy is usually a delicate scenario requiring multidisciplinary care during pregnancy in order to avoid serious complications arising from it.
Kidney stones in children
Children, too, can have kidney stones. The pathology of kidney stones in children is also increasing in the world. In fact, until a few years ago the causes were attributable only to diseases of genetic origin, while today it is increasing due to the poor eating habits of the youngest. Cystinuria is the most frequent cause of kidney stones in children of genetic origin. It is an alteration of a gene that leads to a greater elimination of cystine with the urine that precipitates can form the calculations. This disease has a hereditary transmission. In Europe and in America the frequency with which this disease is recorded is about 1 patient every 15,000-20,000 births.
Kidney stone cases in children are increasing due to poor eating habits. The increased intake of very salty foods, such as chips, and carbonated drinks such as coca-cola are among the main causes. The carbonated drinks in fact contain many oxalates, while junk food contains a large amount of salt which increases the elimination of calcium. A diet in which these foods and beverages are increasingly present together with the habit of not drinking water and therefore having a low dilution are leading to a decisive increase in kidney stones in children. In the US in the last 10 years, cases of pediatric calculosis have increased 7-fold.
A child is a more delicate patient than the adult because it has more fragile organs and because the recurrence of this disease is much higher in children than in adults. For this we must be careful both in medical therapy and in surgery to remove all the fragments of stones to avoid recurrence. The surgery that is applied in cases of kidney stones in children is the same as that done with adults, but with instruments with smaller sizes to penetrate into the urethra and kidney.
Drugs for the treatment of kidney stones
Among the potentially useful drugs to prevent the appearance of ossicalcic nephrolithiasis we remember:
Thiazide diuretics (e.g., hydrochlorothiazide, chlorthalidone and indapamide): have proved to be useful in reducing calciuria and the appearance of nephrolithiasis. Furthermore, these medications induce a positive calcium balance and consequently promote the increase in bone mineral density. Sodium food restriction is indicated during therapy, while potassium intake should be increased to avoid hypokalemia, which in turn may lead to hypocitraturia. The usual starting dose is 12.5-25 mg of chlorthalidone or hydrochlorothiazide. Most patients should be supplemented with potassium citrate. Potassium-sparing diuretics such as amiloride can help prevent hypokalemia, but triamterene should be avoided because of its low solubility.
Alkalizing agents: citrates inhibit the formation and growth of calcium crystals; in general, potassium citrate is preferred, since sodium citrate may favor hypercalciuria
Allopurinol: in case of concomitant hyperuricosuria, since uric acid favors the precipitation of calcium oxalate crystals, allopurinol is useful because it suppresses the synthesis of uric acid, reducing its urinary excretion
Fish oil: reduces the concentration of calcium in the urine, besides the kidney stones is very rare among the Inuit of Greenland; it could therefore be useful in preventing calcium oxalate kidney stones.