Correspondence

Ultrasonographic Evaluation of Melamine-Exposed Children in Hong Kong

N Engl J Med 2009; 360:1156-1157March 12, 2009

Article

To the Editor:

The recent melamine contamination of infant formula and milk products in China placed thousands of children in China and neighboring regions at risk for renal-stone formation and renal failure; six deaths were reported. In the wake of the crisis, screening programs were launched nationwide in the mainland of China. A similar program was initiated in Hong Kong1; here, we describe the results.

From September 28 through October 17, 2008, a total of 2140 children (1177 boys and 963 girls; age range, 1 month to 12 years; mean age, 6.45 years), all asymptomatic, underwent ultrasonographic screening at Prince of Wales Hospital, one of the designated special assessment centers in Hong Kong. On ultrasonography, a stone (nonobstructive, 7 mm in length) was detected in only one child. Another child had increased echogenicity in both renal papillae. Six additional children had small, discrete, hyperechoic renal foci (<4 mm in diameter) near the renal papillae, all of which were associated with “comet-tail” artifacts2 on gray-scale ultrasonography (Figure 1Figure 1Longitudinal Ultrasonogram of the Right Kidney in an 8-Year-Old Girl.). A “twinkling artifact”3 was revealed by color Doppler imaging in two of the six children with hyperechoic foci. Limited low-dose computed tomography of the kidneys was performed in two of the six children and confirmed the presence of calcific foci.

It is unclear whether these echogenic renal foci were related to melamine-crystal deposition or were incidental findings. Renal histopathological characteristics in cats exposed to melamine have been shown to be due to melamine crystals, primarily within the distal tubules.4 It is unknown whether filtered melamine crystals are trapped within the distal tubules in humans, rendering the renal papillae a susceptible site for deposition and aggregation. Currently, there is no noninvasive test that would ascertain the nature of these echogenic foci.

We encouraged the families of the children we screened to ensure adequate hydration, and we have planned for follow-up ultrasonography to be performed in the eight children with abnormal findings, 3 months after the initial studies.

Our current report from Hong Kong indicates that the adverse effects of melamine-tainted milk products do not initially appear to be as severe as first anticipated. In populations exposed to doses of melamine similar to those among the children in Hong Kong,5 screening by means of ultrasonography is likely to identify few findings and findings of unclear clinical relevance.

Stella Sin Yee Ho, Ph.D.
Winnie Chiu Wing Chu, F.R.C.R.
Ka Tak Wong, F.R.C.R.
Chi Kong Li, M.D.
William Wong, F.R.C.P.
Pak Cheung Ng, M.D.
Anil T. Ahuja, F.R.C.R.
Chinese University of Hong Kong, Hong Kong, China
aniltahuja@cuhk.edu.hk

Supported by the government of the Hong Kong Special Administrative Region. The authors are independent of the sponsor.

This letter (10.1056/NEJMc0809955) was published at NEJM.org on February 4, 2009.

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Citing Articles (8)

Citing Articles

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   Hejun Duan, Na Guan, Yongning Wu, Jing Zhang, Jie Ding, Bing Shao. (2011) Identification of biomarkers for melamine-induced nephrolithiasis in young children based on ultra high performance liquid chromatography coupled to time-of-flight mass spectrometry (U-HPLC–Q-TOF/MS). Journal of Chromatography B 879:30, 3544-3550
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   Jian Gao, Hong Xu, Xin-Yu Kuang, Wen-Yan Huang, Nai-Qing Zhao, Jia Rao, Qiang-Ying Qian, Xian-Ying Cheng, Zhi-Min Feng, Jing Xu, Xin Zhang, Xiang Wang. (2011) Follow-up results of children with melamine induced urolithiasis: a prospective observational cohort study. World Journal of Pediatrics 7:3, 232-239
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   Alice PS Kong, Kai-Chow Choi, Chung Ho, Michael HM Chan, Chun Wong, Eric KH Liu, Winnie CW Chu, Viola CY Chow, Joseph TF Lau, Juliana CN Chan. (2011) Hong Kong Chinese school children with elevated urine melamine levels: A prospective follow up study. BMC Public Health 11:1, 354
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   Carl G. Skinner, Jerry D. Thomas, John D. Osterloh. (2010) Melamine Toxicity. Journal of Medical Toxicology 6:1, 50-55
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   Gang Li, Shufang Jiao, Xiangjun Yin, Ying Deng, Xinghuo Pang, Yan Wang. (2010) The risk of melamine-induced nephrolithiasis in young children starts at a lower intake level than recommended by the WHO. Pediatric Nephrology 25:1, 135-141
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   Hang Yee Lau, Chun Sing Wong, Johnny Ka Fai Ma, Elaine Kan, Kwong Lok Siu. (2009) US findings of melamine-related renal disorders in Hong Kong children. Pediatric Radiology 39:11, 1188-1193
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   Feng Yang, Yu Mao, Xiaodong Zhang, Zhiqiang Ma, Xinrong Zhang. (2009) LC-MS/MS method for the determination of melamine in rat plasma: Toxicokinetic study in Sprague-Dawley rats. Journal of Separation Science 32:17, 2974-2978
   CrossRef

8. 8

   Langman, Craig B., . (2009) Melamine, Powdered Milk, and Nephrolithiasis in Chinese Infants. New England Journal of Medicine 360:11, 1139-1141
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