Urolithiasis

Uurolithiasis is a polyetiological disease characterized by the presence of a stone or several stones in the kidneys and/or urinary tract. This is one of the most common urological diseases and occurs in at least 1-3% of the population, most often between the ages of 20-50 years. Patients make up 30-40% of the total population of urological hospitals. Stones are most often localized in the right kidney. Bilateral stones are observed in adults in 15-30% of cases, and in children – in 2.2-20.2%. Despite the changes in the social and demographic living conditions of the population, the remaining endemic foci of morbidity (Central Asia, the Caucasus, the Volga region, the Far North, Australia, the states of the Balkan Peninsula, Brazil, Turkey, India, the eastern regions of the USA, etc.) indicate a significant influence of environmental factors and geographical conditions on the occurrence and development of urolithiasis.

Etiology and pathogenesis. Currently, there is no single theory of the pathogenesis of urolithiasis. The genesis of stone formation is divided into causal (etiological) and formal (pathogenetic).

Etiology (causal genesis). Among the factors of stone formation, the leading place is occupied by congenital enzymopathies (tubulopathies), anatomical malformations of the urinary tract, hereditary nephrosis- and nephritis-like syndromes.

Enzymopathies (tubulopathies) represent disorders of metabolic processes in the body or the functions of the renal tubules as a result of various enzymatic disorders, which can be either congenital or acquired. The most common are the following enzymopathies: oxaluria, uraturia, generalized aminoaciduria, cystinuria, galactosemia, fructosemia, de Toni-Debreu-Falconi syndrome.

Etiological factors for the development of stone formation against the background of congenital tubulopathies can be divided into exogenous and endogenous.
Exogenous factors: geographical, socio-economic, nutritional, gender, age, chemical composition of water, etc. Taking into account exogenous factors, increased stone formation in the warm season, especially in countries with hot climates, is explained by the theory of dehydration (combined with high mineralization of water and increased urine concentration) and loss of sodium in urine. With an increase in the hardness of drinking water and the content of calcium and magnesium in it, the frequency of stone formation increases.

Endogenous factors

General: hypercalciuria, A-vitaminosis, D-avitaminosis or overdose of vitamin D, hyperparathyroidism, bacterial intoxication in general infections and pyelonephritis, consumption of large amounts of certain chemicals (sulfonamides, tetracyclines, antacids, acetylsalicylic acid, glucocorticoids, etc.), prolonged or complete immobilization, etc. d.

Local (leading to disruption of urinary tract): ureteral strictures, primary and secondary stenoses of the ureteropelvic segment, urinary tract anomalies, nephroptosis, vesicoureteral reflux, urinary tract infection, etc. Obstructed outflow of urine from the kidneys leads to impaired excretion and resorption of the constituent elements of urine, loss (crystallization) salt sediment, and also creates conditions for the development of the inflammatory process.

The risk of stone formation increases significantly if there are simultaneously several factors predisposing to the disease in the body.

Pathogenesis (formal genesis).The formal genesis of stone formation is based on colloid-chemical and biochemical processes. According to the theory of catarrh of the pelvis, the organic substance formed as a result of inflammation of the pelvis and desquamation of the epithelium becomes the nucleus of stone formation (matrix). According to the crystalloid theory, oversaturation of urine with crystalloids in quantities beyond the limits of solubility leads to their precipitation and stone formation. According to the colloid theory of stone formation, urine is a complex solution, supersaturated with dissolved mineral salts (crystalloids) and consisting of fine protein substances (colloids). The latter, being in a chemical relationship with crystalloids, keep them dissolved in the urine of a healthy person, i.e., a colloid-crystalloid equilibrium is created. If the quantitative and qualitative relationships between colloids and crystalloids in the urine are violated, pathological crystallization and stone formation may occur. One of the significant factors in stone formation is the urine reaction (pH). It determines the optimum activity of proteolytic enzymes and sedimentation of uric salts.

It is currently believed that the basis of the formal genesis of urolithiasis is tubular lesions of the kidneys, leading to increased formation of mucoproteins that bind protective colloids and neutral mucopolysaccharides, which can form complexes with urinary salts both on the mucous membrane of the renal papillae and in the lumen of the renal tubules in the form of cylinders, turning into microlites. Against the background of tubulopathies (enzymopathies), metabolic disorders, which play the role of etiological factors, the action of various exo- and endogenous, general and local pathogenetic factors occurs.
Urinary stones are concentrically layered crystalline aggregates. Concentric layers are formed as a result of the growth of crystals, between which there are protein substances – mucoproteins and coloring (pigment) substances.

Currently, a mineralogical classification of urinary stones is used. About 60-80% of urinary stones are inorganic calcium compounds.

Oxalates (urine reaction is acidic or alkaline) – stones consisting of calcium salts of oxalic acid, usually dark in color, almost black with a spiky surface, very dense.

Phosphates (urine reaction is acidic or alkaline) – grayish or white stones, fragile, easily broken, often combined with infection.

Urates (urine reaction is acidic) – stones consisting of uric acid and its salts, yellow-brown, sometimes brick-colored with a smooth or slightly rough surface, quite dense.

In most cases, urinary stones have a mixed chemical composition. Cystine, xanthine, and cholesterol stones are rare.

Symptoms.

Clinical manifestations of the disease depend primarily on the location of the stone and are determined by the presence or absence of a violation of the outflow of urine from the kidney and urinary tract infection. At the onset of the disease, if there are kidney stones that do not interfere with the flow of urine, urolithiasis may be asymptomatic. The size of the stone is not decisive in the clinical picture of the disease. Thus, the largest coral stones, being inactive, rarely acutely disrupt the passage of urine through the upper urinary tract and may not cause complaints for a long time until infectious and functional complications appear.

The most characteristic clinical symptoms caused by impaired urodynamics, renal function and associated inflammatory process are pain, hematuria, dysuria, stone passage, rarely anuria (postrenal), pyuria.
Acute pain in the lumbar region (renal colic) is observed in at least 80% of patients with urolithiasis. The cause of renal colic is a sudden disruption of the outflow of urine caused by obstruction (blockage) of the upper urinary tract by a stone. Pain in renal colic is sudden, acute, with periods of relief and repeated attacks, begins in the kidney area or along the ureter and has a typical irradiation down to the iliac, groin, etc. Patients behave restlessly, not finding a body position that would reduce pain.

As a result of a sharp increase in intrapelvic pressure during renal colic, the development of pyelovenous reflux in the fornical zone is possible, which is manifested by chills and total gross hematuria after relief of renal colic. In the occurrence of hematuria, severe venous hypertension in the kidney against the background of acute occlusion of the ureter is of great importance.

Dysuria occurs when stones are located in the juxtavesical and intramural parts of the ureter. Due to reflex influences, pollakiuria occurs, and during renal colic, even acute urinary retention. Due to severe dysuria, erroneous overdiagnosis of cystitis, prostatitis, etc. is possible.

The passage of stones is usually accompanied by renal colic, but may not be painful. The ability to pass spontaneously depends largely on the size and location of the stone, as well as the anatomical and functional state of the upper urinary tract. When a stone remains in the ureter for a long time without a tendency to pass, the functional state of the urinary tract and the kidney progressively deteriorates, up to its death.

In the presence of stones in both ureters or in the case of a ureteral stone in a single (or only functioning) kidney, postrenal anuria may develop, requiring urgent therapeutic measures.
Pyuria (leukocyturia) in urolithiasis is an important symptom indicating the addition of a urinary tract infection, which occurs in 70-80% of patients.

It is more correct to consider this symptom as a manifestation of calculous pyelonephritis, which very often accompanies urolithiasis.

Diagnostics.

It is necessary to detail the complaints and pay attention to the following features of the history: duration and nature of urolithiasis (unilateral, bilateral, recurrent), episodes of stone passage, episodes of hematuria and its nature, possible heredity of the disease, previous treatment methods (conservative and surgical), concomitant diseases (endocrine, gastrointestinal tract, injuries of large bones and joints, etc.).
In the absence of renal colic and chronic renal failure, the patient’s condition may be satisfactory. Pale skin and mucous membranes are observed in patients with concomitant anemia with a severe bilateral process complicated by chronic pyelonephritis and renal failure. Depigmentation of the skin of the legs and feet may indicate vitamin A deficiency or pellagra. Young patients (under 45 years of age) may experience arterial hypertension (renal hypertension). Patients with urate lithiasis are characterized by excess body weight. Particular attention is paid to inspection and palpation of the abdomen and lumbar region. Palpation of the kidneys and light tapping of the lumbar region may reveal pain (positive Pasternatsky’s sign). Palpation and percussion of the bladder is mandatory, since the possibility of chronic urinary retention due to the presence of bladder stones or diseases predisposing to their development (hyperplasia or prostate cancer) cannot be excluded. The study of male patients should end with rectal palpation of the prostate gland, which allows us to identify possible concomitant diseases of the prostate gland (hyperplasia or cancer, prostatitis, stones). When palpating per vaginam, it is sometimes possible to palpate a stone in the perivesical ureter.

Laboratory diagnostics
General blood test. Patients often have normal general blood test results, but during renal colic or an attack of acute pyelonephritis, leukocytosis, a shift in the leukocyte count to the left, an increase in ESR, and concomitant anemia may be detected.
Urine analysis– slight proteinuria (protein 0.03-0.3 g/l), microhematuria (fresh red blood cells), single cylinders may occur. In the presence of calculous pyelonephritis, pyuria (leukocyturia) and bacteriuria are observed. Leukocytes over 10 in the p/z indicate an inflammatory process.
Of clinical importance is the assessment of urine pH (acidic, alkaline) and indicators of the relative density of urine (specific gravity).

Salt crystals can be episodic and often depend on the nature of the diet and urine pH. Uric acid crystals with a pH less than 6.0 are characteristic of urate nephrolithiasis and uric acid diathesis; calcium and magnesium phosphates at pH 7.0 and higher – for phosphate lithiasis and phosphaturia; calcium oxalates – for calcium-oxalate urolithiasis or oxaluric diathesis.

Biochemical examination of blood and urine includes determination of the content of creatinine, urea, calcium, magnesium, inorganic phosphorus, uric acid, etc. Total renal function is determined by the level of urea and creatinine in the blood serum and in daily urine (daily excretion).

Increased calcium levels (hypercalcemia), decreased levels of phosphorus and magnesium in the blood serum are signs of impaired metabolism, which are considered risk factors for recurrent stone formation and require the exclusion of the renal form of primary hyperparathyroidism.

An increase in the level of uric acid (hyperuricemia) in the blood serum is observed with urate nephrolithiasis. Hyperuricemia and hyperuricuria (hyperuricosuria) indicate impaired synthesis of uric acid, which occurs with uric acid diathesis, gout and renal failure.

Hyperphosphaturia may be a manifestation of phosphate diathesis, congenital or acquired as a result of primary diseases of the stomach or central nervous system. More often, phosphaturia is false (pH 7.0 and higher), which depends on alkali-forming bacteria (Proteus).

A study of hormone levels (calcitonin and parathyroid hormone) is carried out in the diagnosis of hyperparathyroidism, especially in patients with staghorn, bilateral and recurrent stones with elevated serum calcium levels.
Zimnitsky’s test is an assessment of the functional state of the kidneys based on the dynamics of urine density (normally 1005-1025) during the day in 8 portions of urine. The test is the most physiological. A decrease in the relative density of urine and monotony of indicators indicate impaired renal function.

Bacteriological examination (culture) of urine makes it possible to identify the microflora of urine and determine the titer of bacteriuria. Bacteriological urine cultures with determination of the sensitivity of microflora to antibacterial drugs make it possible to carry out etiotropic treatment of pyelonephritis, which is one of the causes of recurrent stone formation.
Radiation diagnostics
Ultrasound examination makes it possible to assess the size, position and mobility of the kidneys, the size of the parenchyma, determine the presence and degree of dilatation of the pyelocaliceal system, the localization of the stone(s) and determine its linear dimensions. The ultrasound picture of a kidney stone is characterized by the presence of a hyperechoic area with an acoustic shadow (“track”) distal to it.
Survey radiography is indicated for the purpose of detecting and localizing radiopositive (radiopaque) shadows suspicious for stones in the projection of the kidneys, ureters and bladder. Stones can be radiopositive (radio-opaque), radio-negative (radio-opaque) or low-contrast, which depends on the chemical composition (primarily the presence and amount of the calcium component) of urinary stones. Stones consisting of calcium oxalates and calcium phosphates are clearly visible on radiographs. Stones consisting of uric acid and its salts (urates) are not visible on plain radiographs. The “invisibility” of a stone in a survey image may be due not only to its chemical composition, but also to poor image quality, projection of the stone onto the skeletal bones, and other reasons (ascites, obesity, etc.). Kidney and ureteral stones often have to be differentiated from calcified lymph nodes and phleboliths in the pelvic area, gall bladder stones, stool shadows, and intestinal foreign bodies. Excretory urography helps to clarify the nature and localization of the shadow.

Indications for excretory urography are: a stone (ultrasound and survey X-ray data), the size of which does not allow for spontaneous passage, an X-ray negative stone, ureterohydronephrosis, bilateral nephrolithiasis, relapse of the disease, any pathological changes in the opposite kidney with unilateral nephrolithiasis, doubts about the genesis of renal colic, etc. It is recommended to carry it out in a pain-free period (outside of renal colic). With complete occlusion of the ureter by a stone, a radiopaque substance is located above the stone in the dilated ureter, as if indicating the stone (Lichtenberg’s sign). In the case of an X-ray negative kidney or ureteral stone, a filling defect corresponding to the stone is determined against the background of a radiopaque substance.
Additional X-ray examinations: retrograde (ascending) ureteropyelography, and in the presence of nephrostomy drainage, antegrade pyelography are performed according to indications. Indications for performing retrograde ureteropyelography are doubts regarding the diagnosis of urolithiasis or if the stone is X-ray negative.

Computed tomography details the features of the angio-architectonics and anatomical and functional state of the kidneys and urinary tract, clarifies the localization of the stone (stones) and their structural density (densitometry), identifies possible anomalies of the urinary tract, as well as concomitant diseases of the abdominal organs, etc.

Modern and most informative methods for studying patients with urolithiasis are SCT and MSCT with the possibility of three-dimensional image reconstruction and virtual endoscopy, which detail the size, location and structural density of stones, the anatomical and functional state of the upper urinary tract, which determines the choice of treatment method. Modern types of CT scans detect stones of any location and X-ray positivity.

Magnetic resonance urography allows you to determine the level of obstruction of the urinary tract by a stone without contrast in patients with renal colic and with intolerance to radiopaque substances.

Complications. The most common and serious complication of urolithiasis is acute obstructive pyelonephritis, in the event of which all therapeutic measures should be aimed at stopping the inflammatory process. Chronic calculous pyelonephritis is observed in a significant number of patients (90-98%), and its latent course periodically passes into the active phase in almost 2/3 patients.
The persisting impaired passage of urine against the background of a chronic inflammatory process leads to the development of kidney shrinkage (nephrosclerosis), which is accompanied by a decrease in the functional state of the kidney, and the possible development of nephrogenic arterial hypertension. The most serious complication of urolithiasis is the development of acute and chronic renal failure (ARF and CRF).

Treatment. Comprehensive treatment of patients with urolithiasis should pursue the following goals: to relieve pain and especially an attack of renal colic, to promote the passage of small stones, to remove stones that, due to their size or for other reasons, cannot pass on their own, and to prevent recurrent stone formation.
Drug treatment

1. Antispasmodics and antispasmodic analgesics are used as symptomatic therapy aimed at eliminating an attack of renal colic. Antispasmodic analgesics improve the passage of small stones and reduce tissue swelling during prolonged standing of the stone. The most commonly used drugs are no-sla (drotaverine) and baralgin.

2. Herbal preparations (canephron, cystone, cystenal, phytolysin) are prescribed to patients with urolithiasis, taking into account their diuretic, anti-inflammatory and antispasmodic effects.

3. Preparations for dissolving (litholysis) of urinary stones. Urate stones are subject to medicinal litholysis. Taking into account that urate stones occur against the background of a decrease in urine pH (pH 5.0-5.5), to dissolve them it is necessary to increase the urine pH (pH 6.2-6.8), which is achieved by taking citrate mixtures (blemarene, uralite U). Therapy with citrate mixtures is carried out for 1 to 6 months, while the dissolution of stones is possible after 2-3 months.
4. Medicines aimed at correcting biochemical changes in the blood and urine. To correct purine metabolism, a drug that reduces the formation of uric acid is used – allopurinol (milurite), which inhibits the enzyme xanthine oxidase, which reduces the formation of uric acid, lowers its content in the blood serum, thereby preventing deposition in the kidneys and tissues. Indications for use are urate urolithiasis and other types of urolithiasis occurring with hyperuricemia.

5. Antibacterial and non-steroidal anti-inflammatory drugs are used for the treatment of acute or chronic calculous pyelonephritis. The most commonly recommended are fluoroquinolones (ofloxacin, ciprofloxacin), cephalosporins (cefuroxime, cefazolin, ceftriaxone), aminoglycosides (gentamicin, amikacin, neomycin), carbapenems (thienam), etc.

Antibacterial therapy in patients with urolithiasis is possible only with preserved urine outflow, taking into account the possibility of developing bacteriotoxic shock.
External shock wave lithotripsy. The first session of external shock wave lithotripsy (ESWL or ESWL) was performed in 1980 by Professor Ch. Chaussy (Germany). Over the past years, due to its high efficiency and low invasiveness, it has become widely used and is the method of choice in the treatment of patients with urolithiasis. Modern lithotripters are based on three main principles of shock wave generation: electromagnetic, electrohydraulic and piezoceramic. X-ray or ultrasonic control is used to direct a shock wave at the stone. The effectiveness of remote lithotripsy is determined by the location, size and structural density of the stone, the anatomical and functional state of the upper urinary tract, technical characteristics of the lithotripter, etc.

Optimal for extracorporeal lithotripsy are kidney stones up to 1.5-2.5 cm in size and ureteral stones up to 0.0-1.5 cm in size.
Open surgical interventions. The expansion of clinical indications for extracorporeal lithotripsy, percutaneous nephrolithotripsy, improvement of ureteroscopy and contact ureterolithotripsy techniques have changed the approach to the treatment of patients with urolithiasis – currently the percentage of “traditional” surgical interventions is no more than 5-15%.

Kidney surgeries in patients with urolithiasis can be organ-sapping (nephrectomy) or organ-preserving (pyelolithotomy, partial nephrectomy, nephrolithotomy).

Organ-preserving operations are the main ones in surgical treatment. Ureterolithotomy is used to remove stones from the ureter.

Currently, laparoscopic and retroperitoneal surgery (pyelolithotomy, ureterolithotomy) for patients with urolithiasis is being actively introduced into clinical practice, which is considered as an alternative to open surgery for large kidney stones as the main method of treatment, and when remote or contact crushing is ineffective.

Prevention. Therapeutic measures for urolithiasis should consist not only of removing the stone, but also of carrying out the necessary preventive treatment in order to prevent recurrent stone formation. Relapses of the disease, depending on one or another form of urolithiasis, occur in 10-40% of patients. The variety of causes and clinical forms of urolithiasis makes prevention a complex task, which should be maximally individualized depending on the clinical form of the disease, the chemical composition of urolithiasis, etc. Preventive treatment is based on dietary recommendations, correction of biochemical changes, medicinal litholysis (according to indications), etc. Comprehensive monitoring includes performing general and biochemical blood and urine tests, ultrasound of the urinary system, X-ray examination, etc. d.
The nature of nutrition is one of the significant risk factors for the development of urolithiasis, and therefore diet therapy, adequate maintenance of water balance, etc. play an important role. Dietary recommendations should take into account the results of a chemical analysis of the removed stone and be aimed at correcting biochemical changes.

Dietary recommendations for urate urolithiasis include the exclusion of foods high in purine compounds, such as various meat products, legumes, coffee, chocolate, and cocoa. For calcium oxalate urolithiasis, limit intake of foods high in calcium, ascorbic acid and oxalate. These products include milk and dairy products, cheese, chocolate, green vegetables, black currants, strawberries, strong tea, cocoa. The diet for calcium-phosphate urolithiasis involves limiting the patient’s consumption of foods rich in inorganic phosphorus: fish products, cheese, milk and dairy products. Daily fluid intake should reach 2-2.5 liters per day.

Sanatorium-resort treatment can be used for the purpose of prevention, and under certain conditions, for the treatment of patients. The therapeutic and preventive properties of mineral waters (balneotherapy) lie in their diuretic effect, mechanical washing out of mucus and pus, changing and stabilizing the pH of urine and a beneficial effect on the central nervous system in order to normalize metabolic processes. The following balneological resorts are recommended: Zheleznovodsk (Smirnovsky and Slavyanovsky springs), Essentuki, Kislovodsk (Narzan), Truskavets (Naftusya spring), Borjomi, etc.