title: The relationship between cadmium in kidney and cadmium in urine and blood in an environmentally exposed population.
abstract: BACKGROUND
  Cadmium (Cd) is toxic to the kidney and a major part of the body burden occurs here. Cd in urine (U-Cd) and blood (B-Cd) are widely-used biomarkers for assessing Cd exposure or body burden. However, empirical general population data on the relationship between Cd in kidney (K-Cd), urine, and blood are scarce. Our objectives were to determine the relationship between cadmium in kidney, urine, and blood, and calculate the elimination half-time of Cd from the kidney.
  
  
  METHODS
  Kidney cortex biopsies, urine, and blood samples were collected from 109 living kidney donors. Cd concentrations were determined and the relationships between K-Cd, U-Cd, and B-Cd were investigated in regression models. The half-time of K-Cd was estimated from the elimination constant.
  
  
  RESULTS
  There was a strong association between K-Cd and U-Cd adjusted for creatinine (rp=0.70, p<0.001), while the association with B-Cd was weaker (rp=0.44, p<0.001). The relationship between K-Cd and U-Cd was nonlinear, with slower elimination of Cd at high K-Cd. Estimates of the K-Cd half-time varied between 18 and 44years. A K-Cd of 25μg/g corresponds to U-Cd of 0.42μg/g creatinine in overnight urine (U-Cd/K-Cd ratio: about 1:60). Multivariate models showed Cd in blood and urinary albumin as determinants for U-Cd excretion.
  
  
  CONCLUSIONS
  In healthy individuals with low-level Cd exposure, there was a strong correlation between Cd in kidney and urine, especially after adjustment for creatinine. Urinary Cd was also affected by Cd in blood and urinary albumin. Previous estimates of the U-Cd/K-Cd ratio may underestimate K-Cd at low U-Cd.
authors: Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden. magnus.akerstrom@amm.gu.se
authors: Magnus
authors: M
authors: Akerstrom
authors: Lars
authors: L
authors: Barregard
authors: Thomas
authors: T
authors: Lundh
authors: Gerd
authors: G
authors: Sallsten
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000378:metabolism / Q000652:urine; D002104:Cadmium / Q000097:blood* / Q000652:urine*; D004781:Environmental Exposure / Q000032:analysis; D005260:Female; D006801:Humans; D007668:Kidney / Q000737:chemistry / Q000378:metabolism*; D007672:Kidney Cortex / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D014019:Tissue Donors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002104:Cadmium