Most children with stones in China, Hong Kong, Taiwan lacked conventional symptoms and signs
WEDNESDAY, Feb. 4 (HealthDay News) -- Exposure to infant formula contaminated with melamine was associated with kidney stones in children in China, Hong Kong and Taiwan, though conventional signs and symptoms of nephrolithiasis were lacking, according to a study and two letters published online Feb. 4 in the New England Journal of Medicine.
Na Guan, M.D., Ph.D., of the Peking University First Hospital in Beijing, China, and colleagues analyzed data from 589 children aged 36 months and younger who were screened for urinary tract stones with ultrasonography; 421 of the children had been exposed to contaminated infant formula. Children exposed to formula with high levels of melamine were seven times as likely to have stones as children who drank formula free of melamine, and preterm infants were 4.5 times more likely to have stones as full-term infants, the researchers found. Hematuria was found in 5.9 percent of children with stones, and leukocyturia was found in 2.9 percent.
In an accompanying letter, Taiwanese researchers report on screening 1,129 children near the same time. Nine children in the high-exposure group had nephrolithiasis according to ultrasonography, compared to one child in the control group. None had hematuria or flank pain. In another letter from Hong Kong researchers, 2,140 asymptomatic children were screened and only one stone was found.
"It is remarkable that all three reports describe the absence of conventional symptoms and signs related to nephrolithiasis in the children with stones. Unlike renal stones with other causes in adults and children, which commonly have well-described urinary symptoms and signs, the children with melamine-related nephrolithiasis in Beijing, Taiwan and Hong Kong were largely asymptomatic, with detection on ultrasonography the sole indicator of the condition," writes Craig B. Langman, M.D., in an accompanying editorial. He points out that the absence of hematuria and leukocyturia in the children is unexplained.
Letter from Taiwan
Letter from Hong Kong