title: Low-level cadmium exposure and effects on kidney function.
abstract: OBJECTIVE
  The nephrotoxicity of cadmium at low levels of exposure, measured by urinary cadmium, has recently been questioned since co-excretion of cadmium and proteins may have causes other than cadmium toxicity. The aim of this study was to explore the relation between kidney function and low or moderate cadmium levels, measured directly in kidney biopsies.
  
  
  METHODS
  We analysed cadmium in kidney biopsies (K-Cd), blood (B-Cd) and urine (U-Cd) from 109 living kidney donors in a cross-sectional study. We measured glomerular filtration rate (GFR), cystatin C in serum, albumin, β-2-microglobulin (B2M), retinol-binding protein (RBP), α-1-microglobulin (A1M), N-acetyl-β-d-glucosaminidase and kidney injury molecule 1 (KIM-1) in 24 h and overnight urine.
  
  
  RESULTS
  We found significant positive associations between A1M excretion and K-Cd in multiple regression models including age, sex, weight, smoking and urinary flow rate. This association was also present in never-smokers. A1M was also positively associated with B-Cd and U-Cd. GFR and the other biomarkers of kidney function were not associated with K-Cd. GFR estimated from serum cystatin C showed a very poor correlation with measured GFR. KIM-1, RBP and possibly albumin were positively associated with U-Cd, but only in overnight urine. No associations were found with B2M.
  
  
  CONCLUSIONS
  Our results suggest that A1M in urine is a sensitive biomarker for effects of low-level cadmium exposure. A few associations between other renal biomarkers and U-Cd, but not K-Cd, were probably caused by physiological co-excretion or chance.
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Wallin
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Gerd
authors.initials: G
authors.lastname: Sallsten
authors.affiliation: Department of Occupational and Environmental Medicine, Lund University Hospital, Lund, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lundh
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital and Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Barregard
mesh_terms: D000118:Acetylglucosaminidase / Q000652:urine; D000328:Adult; D000368:Aged; D000510:Alpha-Globulins / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D001706:Biopsy; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D003430:Cross-Sectional Studies; D055316:Cystatin C / Q000097:blood; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects*; D000075322:Heavy Metal Poisoning; D000072596:Hepatitis A Virus Cellular Receptor 1; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000652:urine; D019216:Metals, Heavy / Q000652:urine; D008875:Middle Aged; D011041:Poisoning / Q000652:urine*; D011507:Proteinuria / Q000209:etiology*; D011991:Receptors, Virus; D012177:Retinol-Binding Proteins / Q000652:urine; D012907:Smoking; D055815:Young Adult; D001613:beta 2-Microglobulin / Q000652:urine
chemical_list: D000510:Alpha-Globulins; D015415:Biomarkers; D055316:Cystatin C; C491143:HAVCR1 protein, human; D000072596:Hepatitis A Virus Cellular Receptor 1; D008562:Membrane Glycoproteins; D019216:Metals, Heavy; D011991:Receptors, Virus; D012177:Retinol-Binding Proteins; C016001:alpha-1-microglobulin; D001613:beta 2-Microglobulin; D002104:Cadmium; D000118:Acetylglucosaminidase