title: Gender and urinary pH affect melamine-associated kidney stone formation risk.
abstract: OBJECTIVE
  Melamine was known as a new risk for kidney stone due to recent incidences of milk powder contamination in China. Here, we performed a retrospective study to investigate whether age, gender, and urinary pH affect melamine-associated kidney stone risk.
  
  
  METHODS
  A retrospective review was performed of 217 children aged less than 3 years old. All children had a history of being fed with Sanlu milk powder contaminated by melamine, and underwent a clinical screening on kidney stone in Shenyang from November 2008 to February 2009. A comparison with the Chi-square was conducted between 83 cases and 125 normal subjects. The difference between children's gender, age, and urinary pH was evaluated.
  
  
  RESULTS
  A total of 208 subjects, 136 boys and 72 girls, were included in the study. Significant association was observed between melamine-associated kidney stone risk and gender [odds ratio (OR), 2.03; 95% confidence interval (CI), 1.11-3.74; P=0.02] and urinary pH (OR, 1.78; 95% CI, 1.01-3.11; P=0.04), respectively. Male children were at about twofold increased melamine-associated kidney stone risk compared with female children. Acidic urine showed about 1.78-fold increased melamine-associated kidney stone risk compared with normal urine.
  
  
  CONCLUSIONS
  Our investigation results showed an association of gender and urinary pH with melamine-associated kidney stone formation risk.
authors: School of Life Sciences, Liaoning University, Shenyang, China.
authors: Xiuli
authors: X
authors: Lu
authors: Jing
authors: J
authors: Wang
authors: Xiangyu
authors: X
authors: Cao
authors: Mingxin
authors: M
authors: Li
authors: Chunling
authors: C
authors: Xiao
authors: Takahiro
authors: T
authors: Yasui
authors: Bing
authors: B
authors: Gao