Kidney stones are a manifestation of urolithiasis, characterized by the formation of salt concretions (stones) in the kidneys. Accompanied by aching pain in the lower back, attacks of renal colic, hematuria, pyuria. Diagnosis requires CT and ultrasound of the kidneys, excretory urography, radioisotope nephroscintigraphy, examination of biochemical parameters of urine and blood. Treatment of kidney stones may include conservative therapy aimed at dissolving concretions, or their surgical removal (nephrolithotripsy, pyelolithotomy, nephrolithotomy, ).
ICD 10
N20.0 N20.2
Meaning
Kidney stones (nephrolithiasis) are a common pathology. Specialists in the field of practical urology quite often encounter kidney stones, and stones can form in both children and adults. Men predominate among patients; stones are more often detected in the right kidney, in 15% of cases bilateral localization of concretions occurs.
In urolithiasis, in addition to the kidneys, stones can be detected in the bladder (cystolithiasis), ureters (ureterolithiasis) or urethra (urethrolithiasis). Almost always, initially, concretions are formed in the kidneys and from there descend into the lower parts of the urinary tract. There are single concretions and multiple; small kidney stones (up to 3 mm) and large (up to 15 cm).
Causes
Stone formation is based on the processes of crystallization of urine saturated with various salts and the deposition of crystals on the protein matrix-the nucleus. Kidney stone disease can develop in the presence of a number of concomitant factors. Violation of mineral metabolism may be genetically determined. Therefore, people with a family history of nephrolithiasis are recommended to pay attention to the prevention of stone formation, early detection of concretions by monitoring general urine analysis, ultrasound examination, observation by a urologist.
Acquired salt metabolism disorders may be caused by external (exogenous) and internal (endogenous) causes. Among the external factors, the greatest importance is given to climatic conditions and drinking regime and food ration. It is known that in hot climates with increased sweating and a certain degree of dehydration of the body, the concentration of salts in the urine increases, which leads to the formation of kidney stones. Dehydration of the body can be caused by poisoning or an infectious disease that occurs with vomiting and diarrhea.
In the northern regions, the factors of stone formation can be deficiency of vitamins A and D, lack of ultraviolet light, the predominance of fish and meat in the diet. Drinking water with a high content of lime salts, food addiction to spicy, sour, salty also leads to alkalinization or acidification of urine and precipitation from salts.
Among the internal factors, hyperfunction of the parathyroid glands is distinguished – hyperparathyroidism. The increased work of the parathyroid glands increases the content of phosphates in the urine and the leaching of calcium from the bone tissue. Similar disorders of mineral metabolism can occur with osteoporosis, osteomyelitis, bone fractures, spinal injuries, spinal cord injuries. Endogenous factors also include gastrointestinal diseases – gastritis, peptic ulcer, colitis, leading to a violation of acid-base balance, increased excretion of calcium salts, weakening of the barrier functions of the liver and changes in the composition of urine.
Pathogenesis
The formation of kidney stones occurs as a result of a complex physico-chemical process with violations of the colloidal balance and changes in the renal parenchyma. A well–known role belongs to unfavorable local conditions in the urinary tract – infections (pyelonephritis, nephrotuberculosis, cystitis, urethritis), prostatitis, kidney abnormalities, hydronephrosis, prostate adenoma, diverticulitis and other pathological processes that disrupt the passage of urine.
Slowing down the outflow of urine from the kidney causes stagnation in the cup-pelvis system, oversaturation of urine with various salts and their precipitation, delayed discharge of sand and microliths with urine. In turn, the infectious process developing against the background of urostasis leads to the ingress of inflammatory substrates into the urine – bacteria, mucus, pus, protein. These substances are involved in the formation of the primary nucleus of the future concretion, around which the salts present in excess in the urine crystallize.
A group of molecules forms the so–called elementary cell – micelle, which serves as the original core of the stone. The “building” material for the nucleus can be amorphous sediments, fibrin filaments, bacteria, cellular detritus, foreign bodies present in the urine. The further development of the process of stone formation depends on the concentration and ratio of salts in the urine, the pH of urine, the qualitative and quantitative composition of urinary colloids.
Most often, stone formation begins in the renal papillae. Initially, microliths form inside the collecting tubules, most of which do not linger in the kidneys and are freely washed out by urine. When the chemical properties of urine change (high concentration, pH shift, etc.), crystallization processes occur, leading to the retention of microliths in the tubules and papilla encrustation. In the future, the stone may continue to “grow” in the kidney or descend into the urinary tract.
Classification
According to the chemical composition, there are several types of stones found in the kidneys:
- Oxalates. They consist of calcium salts of oxalic acid. They have a dense structure, black-gray color, a spiky uneven surface. They can form both with acidic and alkaline reactions of urine.
- Phosphates. Concretions consisting of calcium salts of phosphoric acid. In consistency, they are soft, crumbly, with a smooth or slightly rough surface, whitish-grayish in color. They are formed with alkaline urine, grow quite quickly, especially in the presence of infection (pyelonephritis).
- Urata. They are represented by crystals of uric acid salts. Their structure is dense, the color ranges from light yellow to brick–red, the surface is smooth or fine-pointed. They occur with an acidic reaction of urine.
- Carbonates. Concretions are formed by precipitation of calcium salts of carbonic (carbonate) acid. They are soft, light, smooth, and can have different shapes.
- Cystine stones. The composition contains sulfurous compounds of the amino acid cystine. Concretions have a soft consistency, smooth surface, rounded shape, yellowish-white color.
- Protein stones. Formed mainly by fibrin with an admixture of bacteria and salts. The structure is soft, flat, small in size, white in color.
- Cholesterol stones. They rarely occur; they are formed from cholesterol, have a soft crumbling consistency, black color.
Sometimes stones of mixed composition, not homogeneous, are formed in the kidneys. One of the most difficult options are coral-shaped stones, which make up 3-5% of all concretions. Coral-like concretions grow in the pelvis and in appearance represent its cast, almost completely repeating the size and shape of the organ.
Symptoms of kidney stones
Depending on its size, quantity and composition, kidney stones can give symptoms of varying severity. A typical clinic includes lower back pain, the development of renal colic, hematuria, pyuria, and sometimes the independent discharge of a kidney stone with urine. Lower back pain develops due to a violation of the outflow of urine, can be aching, dull, and with a sudden urostasis, with a blockage of the kidney pelvis or ureter, progress to renal colic. Coral-shaped stones are usually accompanied by an indistinct dull pain, and small and dense ones give a sharp paroxysmal pain.
A typical attack of renal colic is accompanied by sudden acute pain in the lumbar region, spreading along the ureter into the perineum and genitals. Reflexively, against the background of renal colic, frequent painful urination, nausea and vomiting, flatulence occur. The patient is excited, restless, can not find a position that facilitates the condition. A painful attack with renal colic is so pronounced that it is often stopped only by the introduction of narcotic drugs. When stones obstruct both ureters, postrenal anuria, fever develops.
At the end of the attack, kidney stones often leave with urine, post-pain hematuria is possible. The intensity of hematuria can be different – from minor erythrocyturia to pronounced macrohematuria. The excretion of pus in the urine (pyuria) develops with inflammation in the kidneys and urinary tract. The presence of kidney stones does not manifest itself symptomatically in 13-15% of patients.
Diagnostics
Recognition of kidney stones is based on anamnesis, a typical picture of renal colic, laboratory and instrumental imaging studies. At the height of renal colic, there is a sharp pain on the side of the affected kidney, a positive symptom of Pasternatsky, soreness of palpation of the corresponding kidney and ureter. To confirm nephrolithiasis is performed:
- Laboratory diagnostics. Examination of urine after an attack reveals the presence of fresh red blood cells, leukocytes, protein, salts, bacteria. Biochemical examination of urine and blood to a certain extent allows us to judge the composition and causes of the formation of stones.
- Ultrasound. With the help of ultrasound of the kidneys, anatomical changes of the organ, the presence, localization and movement of stones are evaluated. Right-sided renal colic must be differentiated with appendicitis, acute cholecystitis, and therefore an ultrasound of the abdominal cavity may be required.
- X-ray diagnostics. Most of the concretions are determined already during the survey urography. However, protein and uric acid (urate) stones do not reflect X-rays and do not give shadows on the overview urograms. They are subject to detection by excretory urography and pyelography. In addition, excretory urography provides information about morpho-functional changes in the kidneys and urinary tract, localization of concretions (pelvis, calyx, ureter), shape and size of stones.
- CT of the kidneys. Computed tomography is the “gold standard” of diagnostics, because it allows you to see concretions of any size and density. If necessary, urological examination is supplemented with radioisotope nephroscintigraphy.
Treatment of kidney stones
Conservative treatment
Treatment of nephrolithiasis can be conservative or operative and in all cases is aimed at removing kidney stones, eliminating infection and preventing the re-formation of concretions. With small kidney stones (up to 3 mm), which can be removed independently, an abundant water load and a diet excluding meat and offal are prescribed.
With urate stones, a dairy-vegetable diet is recommended, alkalizing urine, alkaline mineral waters (Borjomi, Essentuki); with phosphate concretions, taking acidic mineral waters (Kislovodsk, Zheleznovodsk, Truskavets), etc. Additionally, medications that dissolve kidney stones can be used under the supervision of a urologist (for example, citrate therapy for urate concretions).
First aid for renal colic
With the development of renal colic, therapeutic measures are aimed at removing obstruction and pain attack. For this purpose, injections of platyphillin, sodium metamizole, morphine or combined analgesics in combination with atropine solution are used; a warm sedentary bath is carried out, a hot water bottle is applied to the lumbar region. With non-canceling renal colic, novocaine blockade of the spermatic cord (in men) or the round ligament of the uterus (in women), catheterization of the ureter is required.
Surgical treatment
Surgical removal of stones is indicated for frequent renal colic, secondary pyelonephritis, large concretions, ureter strictures, hydronephrosis, kidney blockade, threatening hematuria, single kidney stones, coral stones. With nephrolithiasis, remote lithotripsy is used to avoid any interference with the body and remove fragments of concretions through the urinary tract. With stones up to 2 cm in diameter, the method of “flexible retrograde nephrolithotripsy” can be used, as well as percutaneous nephrolitholapaxy, which allows you to remove the stone through a puncture in the kidney.
Open or laparoscopic interventions for the extraction of stones – pyelolithotomy (dissection of the pelvis) and nephrolithotomy (dissection of the parenchyma) are rarely resorted to, mainly when minimally invasive surgery is ineffective. With a complicated course of kidney stone disease and loss of kidney function, nephrectomy is indicated. After the removal of concretions, patients are recommended spa treatment, lifelong adherence to a diet, and the elimination of concomitant risk factors.
Prognosis and prevention
In most cases, the course of nephrolithiasis is prognostically favorable. After the removal of stones, subject to the instructions of a urologist, the disease may not recur. In adverse cases, calculous pyelonephritis, symptomatic hypertension, chronic renal failure, and hydropionephrosis may develop.
For all types of kidney stones, it is recommended to increase the volume of drinking to 2 liters per day; the use of special herbal preparations; the exclusion of spicy, smoked and fatty foods, alcohol; the exclusion of hypothermia; improving urodynamics through moderate physical activity and physical education. Prevention of complications of nephrolithiasis is reduced to early removal of kidney stones, mandatory treatment of concomitant infections.