(A) Clinical manifestations
1.Unexplained crying, especially during urination, may be accompanied by vomiting.
2.Naked eye or microscopic hematuria.
3.Acute obstructive renal failure, manifested as oliguria or anuria.
4.Stones can be excreted in the urine, such as male infants with stones obstructing the urethra can be manifested as painful urination and difficulty in urination.
5. There may be hypertension, edema, and percussion pain in the kidney area.
(B) Diagnostic points
1.History of feeding Sanlu brand infant formula.
2.One or more of the above clinical manifestations.
3, Laboratory tests: urine routine (visual or microscopic hematuria), blood biochemistry, liver and kidney function, urine calcium/urine creatinine (generally normal), urine red blood cell morphology (non-glomerular-derived hematuria), parathyroid hormone measurement (generally normal).
4. Imaging: Urological ultrasound is preferred. If necessary, CT scan of the abdomen and intravenous urography (contraindicated in the absence of urine or renal failure), and renal nuclear scan is feasible to evaluate the fractional renal function.
5. Ultrasound features of urinary stones in infants and children due to consumption of contaminated Sanlu brand infant formula.
(1) General features: both kidneys are enlarged; parenchymal echogenicity is enhanced, and the parenchyma is mostly of normal thickness; the renal pelvis and calyces are mildly dilated, and the calyces are rounded; if the obstruction is located in the ureteral lumen, the ureter is dilated above the obstruction point; in some cases, the perinephric fat pad and the soft tissue around the ureter are edematous; as the disease progresses, the renal pelvis wall and ureteral wall may appear secondary edematous thickening changes; in a few patients, a small amount of ascites can be detected.
(2) Stone characteristics: most of the stones involve bilateral collecting system and bilateral ureters; ureteral stones are mostly located at the pelvic-ureteral junction, ureteral cross-iliac artery segment and ureteral-vesical junction; stones are crumb-like accumulation, involving a large area, with a faint posterior acoustic shadow, most of them are different from calcium oxalate stones, and the posterior edge of stones can be detected; urinary tract obstruction due to stones is more complete.
(C) Differential diagnosis
1. Differentiation of hematuria: pay attention to exclude glomerular-derived hematuria.
2. Differentiation of stones: stones are usually negative stones that are X-ray permeable and do not show up on urinary radiographs, which can be differentiated from positive stones that are not X-ray permeable, such as calcium oxalate and phosphate.
3, the identification of acute renal failure, pay attention to the exclusion of prenephrosis and renal renal failure.
(IV) Treatment
1, immediately stop using formula containing melamine.
2. Conservative medical treatment: rehydration, alkalinization of urine to promote the discharge of stones; correction of water, electrolyte and acid-base balance disorders. During the course of conservative treatment, urine routine, blood biochemistry, kidney function should be closely checked, and ultrasound should be reviewed (especially pay attention to the degree of expansion of renal pelvis and ureter and changes in stone shape and location). As the stone is loose or sandy, it is more likely to be expelled on its own.
3. Treatment of combined acute renal failure: Firstly, life-threatening conditions such as hyperkalemia should be corrected, such as the application of sodium bicarbonate and insulin, and if conditions are available, blood purification, peritoneal dialysis and other methods should be taken as soon as possible, and if necessary, surgical intervention should be made to relieve stone obstruction.
4.Surgical treatment: If there is no change in stone form and location by conservative medical treatment, and the hydronephrosis and kidney damage are aggravated, or if the kidney failure is not qualified for blood purification or peritoneal dialysis, surgery can be performed to release the obstruction. Cystoscopic retrograde ureteral cannula drainage, percutaneous nephrostomy drainage, surgical excision and stone extraction, percutaneous nephrolithotomy, etc. are available. Because the stones are loose, uric acid component is predominant, and the patient is an infant, extracorporeal shock wave lithotripsy has greater limitations and needs to be considered carefully.
(E) Follow-up
1.For children with stones observed only in outpatient clinic, review after three months of initial consultation.
2. For those hospitalized for stones, review one month after discharge from the hospital.
3.When symptoms related to stones appear, consult the doctor at any time.
(VI) Precautions
1.It is important to identify and differentiate between congenital urinary tract abnormalities, stones that may be due to other causes or stones secondary to abnormalities.
2. CT and MRI are generally not recommended for this group of children.