It is often surprising to learn that hard “stones” like those found in nature can grow in the human body: urinary stones, also known as urinary calculi and urolithiasis. Urolithiasis is a separate disease and its pathogenesis is different from that of common diseases such as infections and tumors. The urinary system can be compared to the “sewer” of the human body, where urine produced by the kidneys is transported through the ureter (the tube connecting the kidneys to the bladder) to the bladder (the body’s organ for storing and emptying urine), and the bladder contracts after a certain amount of urine is passed out of the body through the urethra. The initial site of stone formation is in the kidney. Small stones formed in the kidney can adhere and continue to grow, or they can follow the urine down the “drain” to the bladder, or stay in the physiological narrowing of the ureter, and are called bladder stones and ureteral stones accordingly. Of course, secondary stones can also form in the kidney, ureter and bladder in the presence of obstruction and infection.
Why do stones grow in the human urinary system?
Urinary stones are an abnormal mineralization process in the human urinary system, as opposed to the physiological mineralization process in the human teeth and bones. The causes of urinary stones can be genetic and environmental, with genetic factors being the endogenous cause and environmental factors being the exogenous cause. Genetic factors include genetic polymorphisms and genetic variants that directly lead to metabolic abnormalities in the body. Common metabolic abnormalities include hypercalciuria, hyperoxaluria, hyperuricuria, hypocitraturia, and hypomagnesuria. Environmental factors are mainly related to geography and climate, and the incidence of urolithiasis is much higher in southern China than in northern China. The formation of urinary stones is a complex physicochemical process in which liquid substances in urine are transformed into solid substances, and urinary supersaturation due to high levels of lithogenic substances in urine is the energy source driving stone formation. Of course, human urine also contains factors that inhibit stone formation, such as citrate and magnesium ions. In a normal human body, the contradictory pair of urinary supersaturation and urinary inhibitory factors is always in dynamic balance and stones do not form. Once this balance is disturbed, urinary stones are produced.
Some people are found to have urinary stones only when they have sudden and severe back pain, i.e., renal colic, and a few are found to have urinary stones only when they go to the hospital due to huge hydronephrosis or even renal insufficiency. In addition, kidney stones can lead to kidney infection, fever and back pain.
Therefore, early detection and timely treatment of urinary stones to ensure an unobstructed urinary tract is the only way to effectively avoid damage to the urinary system caused by stones.
The treatment of urinary stones has two main purposes.
One is to remove stones and protect kidney function;
The second is to remove the cause of the disease and prevent the recurrence of stones.
Different treatment options are available depending on the size of the stone and the location of the stone.
Conservative treatment of urinary stones
Most of the kidney and ureteral stones with diameter <6mm, regular shape and no obstruction in the urinary tract below the stone can be excreted by themselves after conservative treatment. Conservative treatment includes hydration therapy, food therapy and drug therapy: 1. Hydration therapy: the most common and effective method to treat stones and prevent recurrence of stones. 2. Food therapy: reduce the intake of specific foods according to the composition of stones and the metabolic abnormalities present in the body (see later). 3. Drug therapy Drugs to promote stone excretion and to correct metabolic abnormalities in the body (see later). In addition, limiting the intake of sodium (salt and MSG), reducing weight and moderate exercise are effective methods.
Surgical treatment of urinary stones
If stones are large or if conservative treatment is not effective, surgical treatment is required, including extracorporeal shock wave lithotripsy, ureteroscopic (rigid and flexible) lithotripsy, percutaneous nephrolithotripsy and laparoscopic or open surgical lithotripsy. The vast majority of stones can now be treated with minimally invasive methods, which can avoid traditional open surgery. Extracorporeal shock wave lithotripsy consists of a focused shock wave emitted from the shock wave source of the lithotripter, which penetrates into the body from outside the body and generates a pressure of up to 50-100 MPa in the focal area of the stone, emitting a continuous shock wave at the target. As the compressive strength of the stone surface is much lower than the pressure and tensile strength of the shock wave focal point, the stone is gradually crushed until it becomes powder or fine sand and is discharged from the body with urine.
Extracorporeal shock wave lithotripsy is preferred for kidney stones ≤ 2.0 cm in diameter and upper ureteral stones ≤ 1.0 cm in diameter. Ureteroscopic lithotripsy is performed by inserting a hard or soft ureteroscope through the urethra into the bladder and then retrograde up the “sewer” into the ureter. Stones in the upper ureter >1.0 cm and stones in the middle and lower ureter can be treated by ureteroscopic lithotripsy. Percutaneous nephrolithotomy is performed by creating a channel from the skin to the kidney through puncture and dilation. After inserting a nephrolithoscope along the channel, the stone is crushed and removed with holmium laser or ultrasound under direct vision with monitor monitoring. Percutaneous nephrolithotomy is preferred for kidney stones >2.0 cm in diameter. Laparoscopic or open surgery lithotripsy is a laparoscopic or traditional open surgery to remove stones from the renal pelvis or ureter. It is mainly used for patients with renal and ureteral stones who have failed to be treated with minimally invasive techniques or who have combined renal and ureteral malformations that require simultaneous treatment.
Prevention of urinary stones
In recent years, although great progress has been made in the surgical treatment of urinary stones, the recurrence rate of stones after treatment remains high. The high recurrence rate of stones is mainly related to the fact that surgeons and patients themselves only focus on treating the stones themselves, while neglecting to treat the cause of the stones. Treatment of the cause of stones is mainly to correct the metabolic abnormalities present in the body and to prevent stone recurrence by taking appropriate drugs according to the stone composition. Urinary stones can be divided into five categories according to their chemical composition: calcium oxalate stones, calcium phosphate stones, magnesium ammonium phosphate stones, uric acid stones and cystine stones.
Preventive measures for calcium oxalate stones.
1, limit the intake of oxalic acid: foods rich in oxalic acid should be avoided, such as rhubarb, mango, spinach and sesame, cocoa (chocolate), tea and nuts (peanuts, almonds and walnuts, etc.) should be consumed in limited quantities.
2, balanced calcium intake: the recommended intake of calcium for stone patients abroad is 800-1000mg/day, while the actual calcium intake in China is only 309mg/day, so the calcium intake should not be strictly controlled.
3.Correct low citrate urine: oral potassium hydrogen citrate drugs such as Youlert can be taken, while citrus fruits contain a large amount of potassium citrate, 100ml of orange juice can improve the PH value by 0.5 units.
4, control hypercalciuria: if urinary calcium > 8 mmol/24 hours, you can take oral dihydrochlorothiazide tablets.
Preventive measures for calcium phosphate stones.
1, should not drink orange juice, cola and other alkaline drinks to prevent alkalinization of urine.
2.Limit the consumption of high calcium, high phosphorus and high protein foods, including fish, meat, cheese, liver and nuts.
3.Control hypercalciuria: you can take oral dihydrochlorothiazide tablets.
4, acidification of urine: can take oral L-methionine or ammonium chloride. Preventive measures for magnesium ammonium phosphate stones.
1, to avoid the kidney area, bladder area and foot cold.
2, best to drink acidic beverages: such as apple juice, cranberry juice.
3, should not drink alkaline beverages: such as orange juice, cola.
4.Control urinary tract infection: take oral antibiotics.
5.Inhibit detoxification enzyme: can be taken orally detoxification oxime acid.
5.Acidification of urine: oral L-methionine or ammonium chloride can be taken. Preventive measures for uric acid stones.
1.Low purine diet: prefer eggs, milk, vegetables, fruits, etc.
2.Limit purine-rich foods: such as meat, fish, shrimp, etc. (<150g/day), less soy products, mushrooms, and avoid eating animal offal.
3.Alkalinize urine: you can eat citrus fruits rich in potassium citrate.
4, should not drink alcohol, so as not to increase the excretion of lactic acid in the urine and cause acidification of urine.
5.Increase the solubility of uric acid: you can take potassium citrate orally.
6.Control uric acid production: oral allopurinol can be taken.
Cystine stones.
1.Lower urinary cystine concentration and reduce the source of urinary cystine: it is advisable to take alkaline drinks orally to ensure a daily urine volume of 3500ml; strictly limit the consumption of high-protein foods, such as meat, eggs, fish and dairy products, with a protein intake of <0.8g/kg body weight/day; strictly limit the consumption of sodium chloride, <5g/day.
2.Improve the solubility of cystine and convert cystine into soluble substance: you can take alkaline citrate, thiopropene and vitamin C orally.