title: Impact of urine concentration adjustment method on associations between urine metals and estimated glomerular filtration rates (eGFR) in adolescents.
abstract: Positive associations between urine toxicant levels and measures of glomerular filtration rate (GFR) have been reported recently in a range of populations. The explanation for these associations, in a direction opposite that of traditional nephrotoxicity, is uncertain. Variation in associations by urine concentration adjustment approach has also been observed. Associations of urine cadmium, thallium and uranium in models of serum creatinine- and cystatin-C-based estimated GFR (eGFR) were examined using multiple linear regression in a cross-sectional study of adolescents residing near a lead smelter complex. Urine concentration adjustment approaches compared included urine creatinine, urine osmolality and no adjustment. Median age, blood lead and urine cadmium, thallium and uranium were 13.9 years, 4.0 μg/dL, 0.22, 0.27 and 0.04 g/g creatinine, respectively, in 512 adolescents. Urine cadmium and thallium were positively associated with serum creatinine-based eGFR only when urine creatinine was used to adjust for urine concentration (β coefficient=3.1 mL/min/1.73 m(2); 95% confidence interval=1.4, 4.8 per each doubling of urine cadmium). Weaker positive associations, also only with urine creatinine adjustment, were observed between these metals and serum cystatin-C-based eGFR and between urine uranium and serum creatinine-based eGFR. Additional research using non-creatinine-based methods of adjustment for urine concentration is necessary.
authors.affiliation: Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Johns Hopkins University School of Medicine, Baltimore, MD, USA; Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA. Electronic address: vweaver@jhsph.edu.
authors.forename: Virginia M
authors.initials: VM
authors.lastname: Weaver
authors.affiliation: Faculty of Medicine, University of Juárez of Durango State, Durango, Mexico; Secretaría de Salud del Estado de Coahuila, Coahuila, México.
authors.forename: Gonzalo García
authors.initials: GG
authors.lastname: Vargas
authors.affiliation: Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Ellen K
authors.initials: EK
authors.lastname: Silbergeld
authors.affiliation: Instituto Nacional de Salud Publica, Centro de Investigacion en Salud Poblacional, Cuernavaca, Morelos, Mexico.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Rothenberg
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, MD, USA; Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Fadrowski
authors.affiliation: Faculty of Medicine, University of Juárez of Durango State, Durango, Mexico.
authors.forename: Marisela
authors.initials: M
authors.lastname: Rubio-Andrade
authors.affiliation: Laboratory of Inorganic and Nuclear Chemistry, Wadsworth Center, New York State Department of Health, Albany, NY, USA; Department of Environmental Health Sciences, School of Public Health, University at Albany, Albany, NY, USA.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Parsons
authors.affiliation: Laboratory of Inorganic and Nuclear Chemistry, Wadsworth Center, New York State Department of Health, Albany, NY, USA.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Steuerwald
authors.affiliation: Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Ana
authors.initials: A
authors.lastname: Navas-Acien
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, MD, USA; Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA; Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Eliseo
authors.initials: E
authors.lastname: Guallar
mesh_terms: D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D004784:Environmental Monitoring; D019652:Extraction and Processing Industry; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D019216:Metals, Heavy / Q000652:urine*
chemical_list: D019216:Metals, Heavy
keywords: Cadmium; Creatinine; Osmolality; Uranium; Urine concentration