Melamine (Melamine), commonly known as “protein essence”, is an important nitrogen heterocyclic organic chemical. This chemical is often used in the production of plastics, glues and flame retardants. Protein is mainly composed of amino acids, and its nitrogen content generally does not exceed 30%, while the molecular formula of melamine contains about 66% nitrogen. The common protein test method “Kjeldahl method” is to estimate the protein content by measuring the nitrogen content, therefore, the addition of melamine will make the protein test content of food high, so that the poor quality food can pass the food inspection agency’s test.
Infants and children can suffer from urinary tract disorders after ingesting milk powder contaminated with high levels of melamine. Infants and children currently suffering from urinary stones are mainly caused by the consumption of infant milk powder with particularly high melamine content. The results of an epidemiological survey conducted in Gansu Province showed that most of the affected children developed the disease 3 to 6 months after ingesting Sanlu brand infant formula with a melamine concentration of up to 2563 mg/kg (the safety threshold in infant formula should be 15 mg/kg).
I. Clinical manifestations
1, unexplained crying, especially during urination, which may be accompanied by vomiting.
2.Naked eye or microscopic hematuria.
3. acute obstructive renal failure, manifested as oliguria or anuria.
4. stones may be excreted in the urine, such as male infants with stones obstructing the urethra may manifest as painful urination and difficulty in urination.
5. There may be hypertension, edema, and painful percussion in the kidney area.
In acute renal failure, other symptoms include weakness, apathy, drowsiness, irritability, anorexia, nausea, vomiting, diarrhea, and in severe cases, anemia, eruption, mouth ulcers, peptic ulcers or bleeding, convulsions, coma, and respiratory distress.
Second, the main points of diagnosis
1. History of feeding with melamine-added infant formula.
2. One or more of the above clinical manifestations.
3. Laboratory tests: routine urine (visual or microscopic hematuria), blood biochemistry, liver and kidney function, urine calcium/urine creatinine (generally normal), urine red blood cell pattern (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 nuclide scan is feasible to evaluate fractional renal function.
Ultrasound examination of urinary stones in infants and children due to consumption of melamine-added formula is characterized by: enlargement of both kidneys; parenchymal echogenicity enhancement, parenchyma mostly of normal thickness; mild dilatation of renal pelvis and calyces, rounding of renal calyces; if the obstruction is located in the ureteral lumen, the ureter is dilated above the point of obstruction; perinephric fat pad and periureteral soft tissue edema in some cases; as the disease progresses, the renal pelvis wall and ureteral wall may appear In some cases, perinephric fat pad and soft tissue edema around the ureter; with the development of the disease, the wall of the renal pelvis and ureter may appear secondary edema and thickening changes; a small amount of ascites may be detected in a few patients.
Treatment
1.Medical treatment
If infants are found to have kidney stones, they can recover as long as they are treated in time; however, if they are delayed for a longer period of time, they may have sequelae. Treatment mainly includes: for a small number of small diameter stones (less than 3 mm) may be excreted with urine and can be treated on an outpatient basis. For children younger than one year, half a sodium bicarbonate tablet (also called a baking soda tablet) dissolved in 500 ml of plain water is taken orally daily; for children older than one year, one sodium bicarbonate tablet dissolved in 500 ml of plain water is taken orally daily. After one week, drink plenty of water until one month later and review the ultrasound of both kidneys. Hospitalized infants can be heavily rehydrated and alkalinized urine, etc.
2.Surgical treatment
The current treatment plan is mainly based on transcystoscopic ureteropelvic intubation and flushing. This method is especially effective for those children who have kidney failure due to eating Sanlu milk powder. However, some children are too small to have a suitable cystoscope to insert into the urethra, or the ureteral orifice is too congested and edematous for ureteral intubation due to stones, or the intubation is not effective, or the child is in critical condition due to huge stones, etc. Open surgery is also chosen.
In conclusion, in the treatment process of children, especially according to the physiological characteristics of infants and children, we should strictly grasp the indications and prefer harmless diagnostic and therapeutic measures to ensure the healthy surgical treatment of children.