title: Low exposure to melamine increases the risk of urolithiasis in adults.
abstract: Melamine, a widely used chemical found in many products in daily use, became a public health concern due to melamine-associated urinary stone formation in children. In adults, it is still unknown whether low-dose melamine exposure may also cause urolithiasis. To address this question, we studied 211 Taiwanese patients diagnosed with calcium urolithiasis and 211 age- and gender-matched controls. All patients completed a detailed questionnaire and provided blood and urine samples for biochemical analysis. Urinary melamine concentrations were measured by triple-quadrupole liquid chromatography tandem mass spectrometry. Compared with those whose urinary melamine levels were below the detection limit of the method, patients with urinary melamine levels of up to 3.11  ng/ml and those with levels of ≥3.12  ng/ml had 3.01- and 7.64-fold increased risk, respectively, of calcium urolithiasis after adjusting for educational level, fluid intake, cigarette smoking, betel quid chewing, alcohol drinking, urinary uric acid, calcium, creatinine, and estimated creatinine clearance rate. The population attributable risk of calcium urolithiasis averaged 50% when melamine was detected in the urine, after considering other covariates. MALDI-TOF mass spectrometry detected melamine in the stones of nine representative patients who had measurable urinary melamine levels. Thus, low-dose melamine exposure can play an important role in calcium urolithiasis in Taiwanese adults.
authors.affiliation: Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Chia-Chu
authors.initials: CC
authors.lastname: Liu
authors.forename: Chia-Fang
authors.initials: CF
authors.lastname: Wu
authors.forename: Bai-Hsiun
authors.initials: BH
authors.lastname: Chen
authors.forename: Shu-Pin
authors.initials: SP
authors.lastname: Huang
authors.forename: William
authors.initials: W
authors.lastname: Goggins
authors.forename: Hei-Hwa
authors.initials: HH
authors.lastname: Lee
authors.forename: Yii-Her
authors.initials: YH
authors.lastname: Chou
authors.forename: Wen-Jeng
authors.initials: WJ
authors.lastname: Wu
authors.forename: Chun-Hsiung
authors.initials: CH
authors.lastname: Huang
authors.forename: Jentaie
authors.initials: J
authors.lastname: Shiea
authors.forename: Chien-Hung
authors.initials: CH
authors.lastname: Lee
authors.forename: Kuen-Yuh
authors.initials: KY
authors.lastname: Wu
authors.forename: Ming-Tsang
authors.initials: MT
authors.lastname: Wu
mesh_terms: D000328:Adult; D002118:Calcium / Q000032:analysis; D016022:Case-Control Studies; D004326:Drinking; D005260:Female; D005506:Food Contamination; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013624:Taiwan; D014227:Triazines / Q000008:administration & dosage / Q000633:toxicity* / Q000652:urine; D014527:Uric Acid / Q000652:urine; D014545:Urinary Calculi / Q000737:chemistry; D052878:Urolithiasis / Q000209:etiology* / Q000652:urine
chemical_list: D014227:Triazines; D014527:Uric Acid; C011907:melamine; D002118:Calcium