Urinary stones, also known as urolithiasis, include kidney stones, ureteral stones, and stones of the bladder and urethra.
It is believed that the etiology of urinary stones is complex, mainly related to the natural environment, racial genetics, metabolic abnormalities (high urinary calcium, high oxalic acid urine, etc.), nutrition and dietary habits (insufficient breast milk, high animal protein, high refined sugar, etc. in children), urological diseases, certain diseases and medications (hyperparathyroidism, paraplegia, long-term bed rest, vitamin D overdose, etc.), which have a direct impact. Infant stones caused by the recent “melamine” incident are another cause of stones.
Stones are stationary, and are characterized by lumbar pain on the affected side, sometimes good, sometimes bad, and are not taken seriously, while such cases have a greater impact on kidney function.
Sometimes strenuous exercise and labor can cause the pain to flare up and worsen. Smaller stones are easily moved and often trigger renal colic. Renal colic is characterized by severe pain in the lower back, pallor, profuse sweating, nausea, vomiting, and abdominal distension. Such patients will mostly seek medical attention in time. Small stones can be excreted by themselves after an attack of renal colic, and clinical examination does not produce positive results. In a few cases, the stones may be hematuria in the naked eye. Occasionally, patients may seek medical attention for painless hematuria. In case of combined infection, there are painful urination, frequent urination and urgent urination. If stones are present on both sides at the same time and cause ureteral obstruction, acute anuria, called stone anuria, may be observed.
The most common method to check urinary stones is ultrasound.
Ultrasound is intuitive, convenient, non-invasive, and can detect stones of 0 or 3 mm or more. The disadvantage is that stones in the middle ureter are often not detected. x-ray urography, can diagnose most urinary stones. Both stones that are impervious to x-rays and stones that can be penetrated by x-rays may be seen. Sometimes stones that are not detected by ultrasound can be detected using imaging and can be helpful in choosing a treatment plan. This is the reason why doctors often ask for a second imaging test after looking at the ultrasound results.
Bad consequences caused by stones
The growth of urinary stones is a longer process. Once the stones are created, they have an impact on the body. When the stones are small, they are unnoticeable to the patient, and as they increase in size, most patients often have back pain and hematuria; on the other hand, when the stones stay in the body for too long, there is secondary damage, mainly urinary tract obstruction, secondary infection and epithelial lesions. In some cases, ureteral obstruction is caused after the stone enters the ureter, resulting in hydronephrosis, renal colic and unbearable pain.
In clinical cases, patients with hydronephrosis mainly suffer from urinary obstruction caused by stones lodged in the ureter. When hydronephrosis is mild, the urinary function of the kidney is still good; in moderate hydronephrosis, the urinary function of the kidney is severely damaged; in severe hydronephrosis, which is not relieved in time, the renal parenchyma is highly atrophied and there is no obvious boundary between the cortex and the medulla, the urinary function of the kidney is basically lost. Urinary tract obstruction can also cause inflammatory reaction caused by non-bacterial infection. Epithelial lesions are mainly the result of irritation of epithelial tissues by renal pelvis and calyx stones in the presence of infection, which can induce carcinogenesis in severe cases. In many patients, stones are temporarily removed with surgical or non-surgical treatment. However, new stones will soon be formed, which is very painful for patients.
The four weapons of minimally invasive surgery for stone treatment
The current measures for treating urinary tract stones are non-surgical and surgical. Smaller stones can be treated non-surgically with drugs that release ureteral spasm and drugs that promote stone expulsion.
Depending on the location of the stone, the surgical procedure used to treat the stone can also vary. The traditional extracorporeal shock wave lithotripsy technique can be used as appropriate when the attack is short, the stone size is not large, and the hydronephrosis is mild. The aim of extracorporeal shock wave lithotripsy treatment is to crush the stones so that they can be easily expelled, but the emptying of the stones depends on the patient’s own efforts. Some people, after most of the stones are expelled, think that the stones will empty on their own and stop paying attention to it. As a result, the remaining small fragments become the core for the formation of new stones, leading to the rapid recurrence of stones. Therefore, after receiving extracorporeal shock wave lithotripsy treatment, patients must visit the hospital regularly for follow-up prevention until the stones are completely discharged.
Larger kidney stones can be removed by lithotripsy under percutaneous nephropuncture. During the operation, the surgeon uses B-ultrasound or X-ray to locate the stone, punctures the patient’s kidney with a fine needle through the lumbar region, extends the lithotripsy instrument into the kidney through an enlarged puncture channel, and uses special lithotripsy equipment to crush the stone and suck it out of the body. Instead of the traditional open surgery, it is the most advanced measure to treat kidney stones.
Upper ureteral stones can also be treated with percutaneous nephrological techniques if there is significant hydronephrosis. Sometimes doctors will use laparoscopic techniques to remove the stones in the ureter on a case-by-case basis. This involves making three to four holes in the lumbar region and using special instruments to cut open the ureter and remove the stone. The laparoscopic ureteral stone removal surgery is faster and does not require open surgery as in the past. The scar is small and does not affect the aesthetics.
For the treatment of lower and middle ureteral stones, the more advanced treatment measure is ureteroscopic lithotripsy to remove stones. The doctor inserts the ureteroscope into the ureter through the urethra and can use advanced equipment such as pneumatic ballast and holmium laser to crush the stones after finding them, which can immediately relieve the renal colic caused by obstruction and reduce the damage to kidney function. Since the procedure is performed through the natural lumen, there is no scar after surgery and recovery is fast.
Find out the original cause of the stone and eradicate the cause
Some stones have a clear cause, and if the primary lesion can be identified and the corresponding treatment measures can be applied, the recurrence of stones can be effectively prevented. For example, hyperparathyroidism (parathyroid adenoma, adenocarcinoma or proliferative changes, etc.) can cause disorders of calcium and phosphorus metabolism in the body and induce calcium phosphate stones. In this case, parathyroid disorders need to be treated first. Factors that cause poor urination, such as urological tumors, prostate enlargement, and urethral strictures, can cause urine to accumulate, resulting in the “aging” of urine. When the organic deposits in urine “age”, they may increase in size and become non-crystalline microstones. Prolonged bed rest in paraplegia can cause disuse decalcification of bones and high urinary calcium. Most intestinal resections, short-circuiting of intestinal anastomosis and chronic gastrointestinal diseases can cause excessive absorption of oxalic acid and lead to hyperoxaluria; excessive vitamin C and aspirin can increase the excretion of oxalic acid; gout, malignant tumors and leukemia can increase the concentration of uric acid in the urine. The children who consumed melamine-contaminated milk powder are suffering from urinary tract uric acid stones due to abnormal metabolism.
In addition, urinary tract infection is a major local factor in urinary stone formation and is directly related to the effectiveness of urolithiasis prevention and treatment. Urinary tract infections caused by Aspergillus, Staphylococcus and Streptococcus are prone to induce stones. These bacteria can break down urea into ammonia, making urine alkaline and prone to urate precipitation and stone formation. In addition, bacteria and the pus masses and necrotic tissues caused by them can also serve as the core of stones and lead to stone formation. Therefore, timely treatment of urinary tract infections is important to prevent stone recurrence.
Stone composition analysis, a powerful tool to prevent stone recurrence
The specific causes of urinary stones are unknown resulting in a variety of stone components. According to the chemical composition of stones, they can be classified as follows: calcium oxalate stones, calcium phosphate stones, uric acid stones, magnesium phosphate amine stones and cystine stones. As stone attacks are extremely painful for patients, there is an urgent need for specialized physicians to provide guidance on the prevention of stone recurrence. Previously, doctors could only make preliminary judgments based on the imaging presentation of the stones and the color of the stones. At present, the patient only needs to provide a sample of stones of the size of a grain of rice, and the physicochemical analysis of the stones is performed by using the current advanced infrared spectroscopy automatic analysis system, so that the composition of the stones can be clarified, and then preventive measures can be proposed in a targeted manner, and the acid-base environment of the urine can be artificially changed through medication or dietary modification, which can help patients minimize and prevent the occurrence of stones. At present, the Department of Urology of the Second Hospital of Soochow University has introduced a new stone infrared spectrum automatic analysis system for urinary stone composition analysis, which provides a new weapon for stone patients to prevent stone recurrence.
How to prevent “crazy stones”
Urinary tract stones, the first in the treatment, the importance of prevention, if patients do not pay attention to life, has been cured of urinary tract stones will soon recur. According to some statistics, the recurrence of urinary stones is more than 10% in 10 years. The recurrence rate of mixed calcium oxalate and calcium phosphate stones can be more than 40%. After treatment with extracorporeal shock wave lithotripsy, the recurrence rate of stones is usually 5-10%. In the case of infected stones with stone fragments remaining after extracorporeal shock wave lithotripsy, the stone recurrence rate can be as high as 78%. Therefore, prevention of recurrence of urinary stones is an essential measure.
(1) Drinking water to prevent stones
Simple attention to drinking water can keep nearly two-thirds of stone patients from producing new stones. Normal people should maintain a urine volume of more than 2000ml every 24 hours, and those who have suffered from stones should maintain a urine volume of 2000 – 3000ml. physical workers or people who work at high temperatures should drink more water because they sweat a lot and their urine is concentrated, so metabolic wastes are more likely to precipitate and form stones. Epidemiological surveys show that people living in tropical areas are prone to urinary stones. The hotter the zone, the more patients with urinary stones. The incidence of urinary stones is also higher in the south of China. This indicates that the formation of urinary stones is significantly associated with high temperatures. In addition, the occurrence of renal colic in patients with urinary stones is also significantly higher than in winter when the temperature rises suddenly in the hot season, which also fully illustrates the importance of drinking water.
Doctors often advise those patients suffering from urinary tract stones to drink more water to help remove stones, however, a considerable number of patients are not drinking plain water but drinking tea, which is not beneficial but harmful. This is because of the large content of oxalic acid in the composition of tea. In addition, some people use drinks instead of plain water, such as often drink oxalic acid-rich drinks, but will greatly increase the incidence of oxalic acid stones. Therefore patients should drink less tea and more plain water. Drinking water should be distributed throughout the day, so in addition to drinking a lot of water during the day, you should also drink 300–500 ml of water before going to bed and after getting up to urinate during sleep. As the excretion of stone components mostly peaks at night and early in the morning, drinking water at this time is most beneficial.
(2) Diet for stone prevention
The production of urinary stones is related to the structure of diet. Therefore, attention to dietary structure can prevent the recurrence of stones. Depending on the composition of urinary stones, different dietary regimens should be adopted. For example, patients with calcium oxalate stones should eat less foods with high oxalic acid content, such as radish, spinach, amaranth, celery, lettuce, bamboo shoots, potatoes and soy products, cocoa, chocolate, black tea, lime, cola and beer; foods with high vitamin C should not be eaten more often such as citrus, lemon, tomatoes and strawberries; oral vitamin B6 and magnesium preparations are beneficial for the prevention and treatment of atopic hyperoxalate urolithiasis.
Calcium-containing stones should be limited to foods rich in calcium and oxalic acid components. Foods high in calcium include milk, dairy products, refined white flour, chocolate, nuts, etc. Excessive intake of calcium and sodium may lead to high urinary calcium, thus increasing the chance of stone formation; sugar and its products, beverages, etc. can increase urinary calcium, which can promote intestinal absorption of calcium and correspondingly increase the absorption of oxalic acid, thus leading to increased urinary calcium excretion, a risk factor for stone formation. Increasing the intake of magnesium and citrate can reduce the risk of urinary stone formation. Consumption of foods containing high calcium such as milk generally does not affect the body’s calcium metabolism and can be consumed normally.
Uric acid stones limit protein intake, eat more fresh vegetables and fruits, should not eat high purine food, such as animal offal, spinach, all kinds of beans, cauliflower, seafood, etc.. Drinking alcohol can increase the level of uric acid and cause urine concentration, so it should not be consumed; excessive intake of animal protein can lead to an increase in calcium and uric acid and a decrease in citrate in the urine, a situation that is an important factor in promoting the formation of urinary stones.
Calcium phosphate and magnesium ammonium phosphate stones.
Stones are mostly formed after infection, and better control of infection is recommended. Alkaline urine predisposes to the formation of magnesium ammonium phosphate stones (urine pH > 7,2). A low-calcium phosphate diet and acidic foods are recommended. All dairy products, lemon juice with phosphate, cola, coffee should be prohibited. Amine chloride can make the urine acidified.
(3) Drugs for stone prevention
Drugs are mostly used to reduce the salt or saturation of stones to prevent stone formation. Alkalizing drugs such as sodium bicarbonate can increase the solubility of cystine and uric acid in urine, but has the effect of reducing urinary magnesium; as potassium citrate can provide a large amount of citric acid and raise the pH of urine, so it has a very prominent therapeutic effect for uric acid stones, low-citrate calcium stones and calcium stones caused by renal tubular toxicity. Allopurinol can reduce intestinal calcium absorption and urinary calcium by inhibiting the formation of prostaglandins: allopurinol can reduce uric acid and also indirectly prevent oxalate stones; oral vitamin B6 can promote the binding of citric acid to calcium in the urine and reduce the chance of calcium oxalate crystallization, which can be used to prevent calcium oxalate stones. D-penicillamine, MPG, acetylcysteine can reduce the saturation of cystine; vitamin C can reduce the formation of cystine from cysteine: the application of acetyl isohydroxamic acid (myclobutanil) in infected stone can inhibit urease, reduce the production of ammonia, and reduce the saturation of ammonium magnesium phosphate and ammonium urate. Taking sodium bicarbonate alkalizes the urine.
In conclusion, the prevention and treatment of patients with urinary tract stones consists of two main aspects.
On the one hand, regular review of ultrasound after stone removal or discharge, and timely treatment if stones are found, can minimize the harm of stones.
On the other hand find out the cause of stone formation and actively treat the primary focus. The stones should also be analyzed for composition and some drugs should be used in a targeted manner to prevent the recurrence of stones. In this way, the “crazy stone” can be swept out of the house to the maximum extent.