title: Association between indoxyl sulfate and bone histomorphometry in pre-dialysis chronic kidney disease patients.
abstract: BACKGROUND
  Experimental studies have suggested that indoxyl sulfate (IS), a protein-bound uremic toxin, may be involved in the development of renal osteodystrophy.
  
  
  OBJECTIVE
  evaluate the association between IS levels and biochemical parameters related to mineral metabolism and bone histomorphometry in a cohort of pre-dialysis chronic kidney disease (CKD) patients.
  
  
  METHODS
  This is a post-hoc analysis of an observational study evaluating the association between coronary calcification and bone biopsy findings in 49 patients (age: 52 ± 10 years; 67% male; estimated glomerular filtration rate: 36 ± 17 ml/min). Serum levels of IS were measured.
  
  
  RESULTS
  Patients at CKD stages 2 and 3 presented remarkably low bone formation rate. Patients at CKD stages 4 and 5 presented significantly higher osteoid volume, osteoblast and osteoclast surface, bone fibrosis volume and bone formation rate and a lower mineralization lag time than CKD stage 2 and 3 patients. We observed a positive association between IS levels on one hand and the bone formation rate, osteoid volume, osteoblast surface and bone fibrosis volume on the other. Multivariate regression models confirmed that the associations between IS levels and osteoblast surface and bone fibrosis volume were both independent of demographic and biochemical characteristics of the study population. A similar trend was observed for the bone formation rate.
  
  
  CONCLUSIONS
  Our findings demonstrated that IS is positively associated with bone formation rate in pre-dialysis CKD patients.
authors.affiliation: Jules Verne University of Picardy.
authors.forename: Fellype Carvalho
authors.initials: FC
authors.lastname: Barreto
authors.affiliation: Jules Verne University of Picardy.
authors.forename: Daniela Veit
authors.initials: DV
authors.lastname: Barreto
authors.affiliation: Federal University of São Paulo.
authors.forename: Maria Eugênia Fernandes
authors.initials: ME
authors.lastname: Canziani
authors.affiliation: Federal University of São Paulo.
authors.forename: Cristianne
authors.initials: C
authors.lastname: Tomiyama
authors.affiliation: Federal University of São Paulo.
authors.forename: Andrea
authors.initials: A
authors.lastname: Higa
authors.affiliation: Jules Verne University of Picardy.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Mozar
authors.affiliation: University Hospital Gent.
authors.forename: Griet
authors.initials: G
authors.lastname: Glorieux
authors.affiliation: University Hospital Gent.
authors.forename: Raymond
authors.initials: R
authors.lastname: Vanholder
authors.affiliation: Jules Verne University of Picardy.
authors.forename: Ziad
authors.initials: Z
authors.lastname: Massy
authors.affiliation: Federal University of São Paulo.
authors.forename: Aluizio Barbosa
authors.initials: AB
authors.lastname: de Carvalho
mesh_terms: D001842:Bone and Bones / Q000033:anatomy & histology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007200:Indican / Q000097:blood*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000378:metabolism* / Q000473:pathology*
chemical_list: D007200:Indican