Renal screening in children after exposure to low dose melamine in Hong Kong: cross sectional study

Abstract

Objective To investigate the renal outcomes of children after exposure to low dose melamine in Hong Kong.Design Cross sectional study.Setting Special assessment centres, Hong Kong.Participants 3170 children (1422 girls and 1748 boys) aged 12 years or less referred from territory-wide primary care clinics after daily consumption for one month or more of milk products tainted with melamine.Main outcome measures Presence of renal stones and haematuria.Results One child had a confirmed renal stone, seven were suspected of having melamine related renal deposits, and 208 (6.6%) were positive for blood in urine by reagent strip. A proportion of these children were followed up at the special assessment centre, but only 7.4% of those positive for blood on reagent strip were confirmed by microscopy, suggesting an overall estimated prevalence of less than 1% for microscopic haematuria.Conclusions No severe adverse renal outcomes, such as acute renal failure or urinary tract obstruction, were detected in children after exposure to low dose melamine. Our results were similar to territory-wide findings in Hong Kong. Even including the seven children with suspected renal deposits, the prevalence of suspected melamine related abnormalities on ultrasonography was only 0.2%. None of these children required specific treatment. The prevalence of microscopic haematuria was probably overestimated by the reagent strip. These data suggest that large scale and urgent screening programmes may not be informative or cost effective for populations who have been exposed to low dose melamine.

Nephrolithiasis associated with the use of topiramate in children

“…In Hong Kong, a 2008 community screening programme in children exposed to melamine-tainted milk products revealed a kidney stone prevalence of 0.03% to 0.27% although these children were otherwise healthy. 8,9 Our study is the first report in a Chinese population of screening for asymptomatic nephrolithiasis in children with COMMENTARY epilepsy managed with TPM. The development of nephrolithiasis in our TPM users was much more common compared with the local general paediatric population.…”

Melamine Toxicity

“…The levels in the two US products were below the 1 ppm current standard for infant formula and were <1/10,000 of the melamine concentrations in many of the contaminated Chinese infant formulas. After the outbreak in China, a Hong Kong study of 3,170 patients younger than 12 years who were ingesting an estimated dose of 0.01-0.21 mg kg −1 day −1 of melamine did not show an increased incidence of kidney stones [41].…”

“…Stones that were later analyzed showed melamine-urate crystals in near equimolar amounts with no evidence of cyanuric acid [14,36,37]. Compared with adults, infants excrete five to eight times the amount of uric acid, a potential predisposing factor toward melamine-urate stone formation [38][39][40][41]. Infants with inborn errors of metabolism, leukemia, lymphoma, or other illness that increases uric acid secretion potentially may have increased risk of stone formation from melamine.…”

“…Melamine stones also appear to be radiolucent [49]. Evaluated stones ranged in size from small and sand-like to as large as 9 mm [37,41,50]. Ultrasound for detection of stones in China and Taiwan yielded mixed results [37,49,50].…”

Issues associated with formula milk: the Hong Kong’s experience

“…The pick-up rate for kidney stones was less than one in a thousand, and the chances of Hong Kong citizens being affected were very low. [3] Anyhow, 18 designated clinics provided initial assessment to nearly 55 thousand patients, while nine assessment centres attended to 25 000 thousand patients.…”