The incidence of uric acid stones has increased with the improvement of living standard and diet structure [1]. Among all types of stones, lithotripsy is more effective in treating uric acid stones. From September 2001 to April 2005, we treated 16 cases of uric acid stones and gained some experience. We report the following. 1. Data and methods 1.1 Clinical data 16 patients with uric acid stones, 13 males and 3 females, aged 30-81 years old, average 53.2 years old. 14 cases of upper urinary tract stones: 3 cases of multiple left kidney stones, including 1 case with left ureteral stone; 3 cases of right kidney stones, including 1 case of stone located in the ureteral junction of the renal pelvis, 2.2 cm × 1.5 cm in size, with the right renal collecting system The minimum stone size was 0.7 cm×0.9 cm and the maximum stone size was 2.3 cm×3.7 cm. The total number of stones in each kidney was judged to be 3-12 on CT films and retrograde films, ranging from the upper, middle, lower or glenoid of the calyx. There were 3 cases of unilateral hydronephrosis and 6 cases of bilateral hydronephrosis; 2 cases of bilateral kidney stones and 2 cases of divided kidney stones had a history of back pain and hematuria, 3 cases of bilateral kidney stones and 1 case of right kidney stones had a history of gout; blood biochemical results showed hyperuricemia in 6 cases, including 5 cases of multiple stones in both kidneys and 1 case of multiple stones in the left kidney; 6 cases of renal function abnormalities, 2 cases of liver function abnormalities (elevated transaminases), 2 cases of hepatitis B surface antigen positivity, and 1 case of combined type 2 diabetes mellitus. Two patients with bladder stones were diagnosed as prostatic hyperplasia. All patients were routinely examined by urological ultrasound, X-ray abdominal plain film (KUB) and intravenous urography (IVP), and patients who did not show up on IVP were examined by retrograde urography with negative KUB and filling defects on IVP or retrograde urography. Cystoscopy was used in patients with bladder stones. Blood biochemistry including liver and kidney function, electrolytes and blood uric acid were examined. All stone specimens obtained were analyzed for composition. 2) Treatment: 12 patients with unilateral ureteral stones in kidney and 2 patients with uric acid stones in bladder were given 3g of sodium potassium hydrogen citrate granules (trade name: Yulite, produced by MADAUS AG, Germany) 3 times/d. The pH value of urine was measured by the pH test paper provided by the pharmaceutical company before taking the drug, and the drug dose was adjusted according to the pH value of urine to make the pH value of urine around 6.8. In a case of double ureteral stones and acute anuria, after the failure of D-J tube placement, a modified Folley incision was made to remove the stone on the severely obstructed side, and then sodium potassium hydrogen citrate granules were administered after the urine volume exceeded 500 mL for 24 hours. In one patient with left renal pelvis stone and hydronephrosis and multiple stones in the right kidney with renal insufficiency (24-h urine volume of 450 mL), the patient was given sodium potassium hydrogen citrate pellets after left pelvic dissection and 0.1 g of allopurinic acid 3 times/d for patients with uric acid above 460 mmol/L. The patient was asked to drink more water to maintain a daily urine volume of about 2,500 mL. Patients were advised to consume less purine-rich foods such as animal offal during the course of the medication. One patient with a left pyelotomy had a postoperative decrease in creatinine from 396.0 mmol/L to 140.5 mmol/L. Two stones of 0.4 cm in diameter were discharged with the addition of sodium potassium hydrogen citrate granules for 20 d. No stones were seen on ultrasound after 8 months. One patient with acute anuria and double ureteral stones took Yulite after emergency surgery (urine output exceeded 600 mL on the same day), and one stone of 0.5 cm in size was discharged after one month, and renal function returned to normal. Eight patients with multiple stones in one or both kidneys and two patients with bladder stones had no stones on ultrasound after 3-8 months of treatment (average 129 d). No cardiovascular or alkalinized urine complications occurred during treatment. Two cases of colic occurred during the downstream process after dissolution of kidney stones, which were relieved by the anal application of diclofenac sodium suppositories. The patients were followed up for 1~42 months, and no recurrence of stones was seen in the cured patients with irregular use of alkalinizing drugs. Urolithiasis is the first common disease in urology, mostly seen in adult males, which directly affects kidney function and is very harmful. Uric acid stones account for about 13% of the total incidence, and pure uric acid stones are the most common negative stones. Uric acid (2,6,8-trioxopurine) is the oxidative breakdown product of purine bases and has no physiological function in the body. The daily production of uric acid in general is 600~800mg, while the same amount of uric acid is excreted from the body. Decreased solubility and supersaturation of uric acid in the urine is a prerequisite for the formation of uric acid stones. Factors that contribute to the decrease in uric acid solubility include a decrease in urine pH, an increase in uric acid volume and a decrease in urine output. No clear inhibitors of uric acid stone formation have been identified so far [1]. The clinical presentation of uric acid stones is nonspecific. The diagnosis of uric acid stones can be made with the help of CT. The density of uric acid stones on CT films is 300-400 Hu, much lower than that of cystine stones, but much higher than that of lesions such as blood clots and tumors. The urine is persistently acidic, with a pH below 6.0, and most of them are below 5.5. The urine sediment examination reveals reddish uric acid crystals, which are occasionally found in detached epithelial cells. The blood and 24-h urine levels of uric acid may be elevated, but this is not diagnostic. Therefore, the diagnosis of uric acid stones requires 3 conditions: (1) negative KUB; (2) filling defect in the renal pelvis or calyces on urography; (3) ultrasound or CT to confirm that the filling defect is due to a stone. However, it should be noted that KUB is difficult to detect stones when they are small in size, low density, poor radiographic quality, and poor bowel preparation, so the actual positive rate of KUB in clinical practice is about 33% [2]. Uric acid stones are solid without slits, and the contrast agent cannot reach the inside of the stone, so the filling defect is clear, unlike the filling defect of tumors with a clot, especially renal pelvis cancer. Reversing the factors that promote the formation of uric acid stones is the basis of prevention and treatment of uric acid stones, while complete dissolution can be achieved by alkalinizing the urine, which is the key to dissolving stones [3-4]. Uric acid is a weak organic acid, half of which is in the form of non-dissociated uric acid at pH 5.35, and half of which is in the form of monovalent urate anion. When the urine is alkalized, the insoluble uric acid is converted into the easily soluble urate anion. When the pH of urine is close to 7.0, it can not only prevent the formation of uric acid stones, but also dissolve the formed uric acid stones, and reduce the intake of nucleic acid-rich food, inhibit the production of uric acid in the body and increase the volume of urine can accelerate the dissolution of stones. It is estimated that the dissolution rate of pure uric acid stones can reach 1 cm/month when the alkalinization effect is good. Uric acid stones generally do not require open surgery. Only with urinary tracts surgical treatment is required, so conservative treatment is often preferred, and alkalinization of urine is the most effective method of lithotripsy. Sodium potassium hydrogen citrate granules can change uric acid into soluble urate, reduce urinary calcium ion concentration, and increase urinary citrate excretion. It can significantly improve the success rate of uric acid stone removal in ureter and shorten the time of stone removal. The mechanism of action may be related to the lysis effect of Youlert on uric acid stones [5]. It is the drug of choice for alkalinizing urine because it does not have the disadvantages of sodium bicarbonate, which increases the sodium load in the body, and it can prevent the formation of calcium-containing stones. The addition of allopurinol in patients with high uric acid can inhibit xanthine oxidase, thus reducing uric acid production, and also reduce the amount of purine nucleotides synthesized de novo in the body, thus indirectly reducing the amount of uric acid production. It is generally believed that systemic alkalinization lithotripsy is suitable for pure uric acid stones without obstruction or only partial obstruction without obvious fluid retention and urinary tract infection; because the secretion and reabsorption of the kidney continue when there is complete obstruction, the purpose of local alkalinization can be achieved, and it is still possible to make the stones small and diuretic after moving, and then the stones are dissolved. In this group, one case of double kidney stone with oliguria and liver insufficiency and one case of double ureteral stone with anuria were treated by open extraction of one side of the stone, which is important to shorten the time of hepatorenal syndrome and promote the recovery of postoperative systemic condition, and to ensure the safety of alkalizing urine drugs in the later stage, which proved to be desirable. Lithotripsy Lithotripsy is painless and inexpensive, and it can dissolve the microstones present in the kidney parenchyma, prevent the further development of uric acid nephropathy, and avoid the trauma caused by surgery. Since the treatment phase of lithotripsy is relatively long, it is necessary to take into account the patient’s general and special conditions during the treatment process, and to actively take effective measures to remove the obstruction as soon as possible to avoid further damage to the kidney unit. After the disappearance of the stone, follow-up and preventive measures should be strengthened, and the recurrence of renal uric acid stones can be prevented by using alkalizing drugs from time to time.