Growth of Children with Urolithiasis Associated with Melamine-contaminated Milk Powder: A Follow-up Study

Objective: To study the impact of melamine-contaminated milk powder on children's growth and development and the elimination of urinary tract stones. Patients and Methods: Seventy-three patients aged ≤4 years with ultrasonographically diagnosed urolithiasis after intake of contaminated milk powder were compared with 79 healthy controls. Assessment included indicators of growth and development based on reference data from World Health Organisation (WHO) standards, Brightness mode (B-mode) ultrasonography as well as urine and blood lab analysis. Results: According to WHO standards, whether at time of diagnosis or 18 months after follow-up, urolithiasis patients all showed generally lower z-scores, compared with control. At time of diagnosis, the differences were statistically significant for weight-for-age, weight-for-length and head circumference in children age ≤2 years and for weight-for- age, length/height-for-age and head circumference in the age groups 2 to 3 years and 3 to 4 years (all p<0.05). Eighteen months after follow-up, urolithiasis patient, had significant smaller values for length- for-age in children age ≤2 years and for weight-for-age, length/height-for-age and head circumference in the age groups 2 to 3 years and 3 to 4 years (all p<0.05). While the patient group and the control showed no statistically difference between diagnosis and 18 months follow-up. On follow-up B-mode ultrasonography 18 months after the diagnosis, five (6.85%) children still showed intrarenal calculi, one (1.37%) child suffered from hydronephrosis. Serum levels of alanine aminotransferase, creatinine and uric acid were within normal range. Proteinuria was not observed. Conclusions: Consumption of melamine- contaminated milk power affects growth and development. Melamine-associated urolithiasis can persist for longer periods of time after cessation of melamine intake. A significant long-term effect of contaminated milk powder on liver and kidney function was not observed.