Clinical manifestations (a) unexplained crying, especially when urinating, may be accompanied by vomiting; (b) naked eye or microscopic hematuria; (c) acute obstructive renal failure, manifested as oliguria or anuria; (d) urinary stones can be discharged, such as male infants with stone obstruction of the urethra can be manifested as pain in the urine, urinary difficulties; (e) hypertension, edema, renal pain on percussion. Diagnostic points (a) Sanlu brand infant formula feeding history. (b) One or more of the above clinical manifestations. (C) Laboratory tests: urine routine (visual or microscopic hematuria), blood biochemistry, liver and kidney function, urinary calcium/urinary creatinine (usually normal), urinary erythrocyte morphology (non-glomerular hematuria), parathyroid hormone measurement (usually normal). (iv) Imaging: Ultrasound of the urinary tract is preferred. If necessary, abdominal CT scanning and intravenous urography (anuria or renal failure is contraindicated), with conditions feasible renal nuclide scanning evaluation of subrenal function. Ultrasound examination of urinary stones in infants and children caused by consumption of contaminated Sanlu brand infant formula: General features: enlargement of both kidneys; parenchymal echogenicity enhancement, the parenchyma is mostly of normal thickness; mild dilatation of the renal pelvis and calyces, and the calyces are rounded; if the obstruction is located in the lumen of the ureter, the dilatation of the ureter is above the point of obstruction; perirenal fat pads and the periureteral soft tissues of some cases are edematous; with the progression of disease, secondary ureteral and pelvic walls may appear. With the development of the disease, the wall of the renal pelvis and the ureteral wall may appear secondary edema and thickening changes; a small amount of ascites can be detected in a few patients. Characteristics of stones: most of the stones involve bilateral collecting system and bilateral ureter; ureteral stones are mostly located in the renal pelvic-ureteral junction, ureter across the iliac arteries and uretero-vesical junction; stones are crushed and accumulated, with a large scope of involvement and pale shadow at the back, most of which are different from calcium oxalate stones, and the posterior edge of the stones can be detected; the ureteral obstruction caused by the stones is more complete. Differential diagnosis (a) hematuria differentiation: pay attention to exclude glomerular hematuria. (B) identification of stones: stones are generally X-ray negative stones, urinary X-ray film does not show, and can be differentiated from X-ray positive stones such as calcium oxalate, phosphate. (C) the identification of acute renal failure, except pre-renal and renal renal failure. (a) Immediately stop using Sanlu brand infant formula. (B) Conservative internal medicine treatment: replenish fluids, alkalize urine, promote the discharge of stones; correct water, electrolyte and acid-base balance disorders. In the course of conservative treatment, urine routine, blood biochemistry, renal function and ultrasound should be closely examined (especially pay attention to the degree of dilatation of the renal pelvis, ureter and changes in the morphology and location of the stones). Since the stones are loose or sandy, they are more likely to be expelled on their own. (C) Treatment of combined acute renal failure: first of all, life-threatening conditions such as hyperkalemia should be corrected, such as the application of sodium bicarbonate and insulin, and blood purification and peritoneal dialysis should be adopted as soon as possible if conditions are available, and surgical intervention should be carried out to relieve stone obstruction if necessary. (D) Surgical treatment: If the shape and location of stones do not change after conservative medical treatment, and the hydronephrosis and renal damage aggravate, or if the renal failure does not have the condition to carry out blood purification or peritoneal dialysis, the obstruction can be lifted surgically. Cystoscopic retrograde ureteral cannulation and drainage, percutaneous nephrostomy and drainage, surgical incision and stone extraction, and percutaneous nephrolithotomy can be chosen. Because the stone is loose, the uric acid component is dominant, the patient is an infant, extracorporeal shock wave lithotripsy has greater limitations, need to be carefully considered. After treatment, the child can be discharged from the hospital if the stone obstruction is lifted, the general condition improves, the renal function returns to normal, and the urination is smooth. Follow-up after discharge: urine routine; urinary ultrasound; renal function tests; if necessary, intravenous pyelography.