| Background:Contamination of dairy products with melamine in China has resulted in a widespread outbreak of urinary tract calculi in infants and children in September 2008. Previous studies found significant correlation between urinary stones infants and melamine-tainted milk.A total of 15577 children fed with melamine tainted milk or infant formula were screened for urinary tract calculi in our hospital after the incident from September to October 2008. Ultrasonography was performed in all the children. For those found with urinary tract calculi on ultrasonography, weight, height, and head circumference of the children were recorded and analyzed. They noted that children with renal calculi had lower weight and head circumference SDSs than the children without renal calculi. The finding is consistent with the fact that melamine contaminated milk formula had lower nourishments, including protein. However the infants and young children require large amounts of protein because of the rapid growth and development. The recent growth and development of infants and young children with urinary calculi is worse than that without urinary calculi. However, there seems no study having reported the long-term effect of melamine-tainted milk powder on growth and development in affected infants and young children. Follow-up study was performed on the children who had evidence of nephrolithiasis or hydronephrosis at screening using renal ultrasonography after three and six months by JM Liu et al. They noted that renal abnormalities persisted in 12% of the affected children at the six-month follow-up, suggesting a need for further follow-up.Objective:This study was to analyze the indicators of the children with urinary tract calculi resulted by melamine tainted milk powder in September 2008 comparing with that of the normal children attended the medical examination in health service centers for community of the Changhe street according to the 2005 China Growth Standards for children under 7 years old and the WHO growth standards, and to assess the growth and development of the affected children. In addition, we performed ultrasonography, routine blood and urine tests, blood biochemistry including renal-function and liver-function tests and Mg2+ tests to discuss the long-term effect of melamine tainted milk powder on infants.Methods:Calculus group:Seventy-three infants were reviewed who had been suffered from stones of the urinary system caused by melamine contaminated milk formula in 2008 in Zhejiang Province. They are aged from 19 months to 48 months, including 13 subjects below 24 months,35 subjects between 24 months and 36 months, and 25 subjects aged from 36 months to 48 months.Control group:Seventy-nine normal children attended the medical examination in health service centers for community of the Changhe Street in Binjiang district, Hangzhou city, where the workers engaged in industry from other provinces gathered. They haven't the history of feeding with contaminated milk products or formula, urinary tract calculi and congenital and chronic diseases. They are aged from 18 months to 47 months.17 subjects are below 24 months.42 subjects are aged from 24 months to 36 months and 20 subjects between 36 months and 47 months.The questionnaire included name, gender, birth of date, family address, and way of contact. Calculus group also included birthplace, feeding method, type of mike powder, time started and finished feed, duration of feed milk powder, the education level and working place of parents, any crying, vomit, hematuria, frequent micturition and odynuria symptoms.Subsequent visit included measure subjects'height, weight and head circumference. The height and weight were used to calculate the weight-for-height. The formula is weight (kg)/height (cm), using the 2005 China Growth Standards and the WHO growth standards to assess subject's development status.Ultrasound was used to re-test the outcome of kidneys, ureter and bladder. Routine blood test, blood biochemistry, Mg2+ tests were used to investigated any changes in leukocyte, RBC, platelet, hemoglobin, total protein, albumin, globulin, GPT, GOT, alkaline phosphatase, cholinesterase, creatinine, urea nitrogen, uric acid, and Ca2+, P, Mg2+. Routine urine test were used to investigate any increased in the index of urine RBC, urine WBC and urine protein. And then discuss the long-term effect of melamine-tainted milk in infants with urinary stones.Results:1.73 cases of calculi group were fed with melamine tainted milk powder mostly produced by the Sanlu Group (58.8%), starting from birth early to no later than 26 months with an average of 3 months and continuing from 1 month to 30 months long with an average of 11 months.83.6% of the children's parents are workers come from other provinces or rural areas.6 cases of parents of children complain of crying,3 parents complain of frequent urination, parents of 1 child complain of urinary urgency.2. The children's weight, height and head circumference in calculi groups are lower than control groups. Below 2 years old, the differences of weight, height and head circumference between the calculi group and control group are not statistically significant (P> 0.05), while from 2 years to 4 years the differences of weight, height and head circumference between the calculi group and control group are statistically significant (P<0.05).3. The weight-for-age Z-scores, height-for-age Z-scores, weight-for-height Z-scores and head circumference-for-age Z-scores of 2005 China Growth Standards in children of calculi groups are generally lower than the control groups, In the weight-for-age and height-for-age below 2 years old, the weight-for-age, the height-for-age and the head circumference-for-age from 2 years to 4 years, The differences between calculi groups and control groups are significant (P<0.05). In children of calculi group, the average weight-for-age Z-score is -0.33, the average height-for-age Z-score is -0.47, the average weight-for-height Z-score is -0.07, the average head circumference-for-age Z-score is -0.12, while in the children of control group are 0.51,0.42,0.36 and 0.51. No difference in the incidence of low weight, growth retardation and wasting between the calculi group and control group.4. The weight-for-age Z-scores, height-for-age Z-scores, weight-for-height Z-scores and head circumference-for-age Z-scores of WHO Growth Standards in children of calculi groups are generally lower than the control groups, In the height-for-age below 2 years old, the weight-for-age, the height-for-age and the head circumference-for-age from 2 years to 4 years, The differences between calculi groups and control groups are significant (P<0.05). In children of calculi group, the average weight-for-age Z-score is -0.10, the average height-for-age Z-score is -0.39, the average weight-for-height Z-score is 0.14, the average head circumference-for-age Z- score is -0.02, while in the children of control group are 0.64,0.58,0.44 and 0.54. No difference in the incidence of low weight, growth retardation and wasting between the calculi group and control group.5. Ultrasounds re-test in calculi group find that 5 patients (6.85%) still have urinary stones,1 patient (1.37%) has hydronephrosis. Children of different age groups show no difference.6. The white blood cells, red blood cells, platelets and hemoglobin values are within the normal reference range in calculi group and control group except 1 with anemia, hemoglobin 99g/l in calculi group, blood biochemical examination of total protein, albumin, globulin, total bilirubin, aspartate aminotransferase, alanine aminotransferase, creatinine, urea nitrogen, uric acid, alkaline phosphatase, cholinesterase, calcium and phosphate ions, magnesium ions of stone group and control group are also within the normal reference range. Routine urine examination of calculi children shows white cell-positive in 1 case (1.39%), red cells positive in 5 patients (6.94%), urine protein negative.Conclusion:1. Subjects fed with melamine-tainted milk have lower growth and development indicators than normal children.2. The urinary stones caused by melamine-tainted milk in some affected children may remain long time.3. No significant negative effect is found in liver and kidney function.
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