title: Is there a relationship between tryptophan dietary intake and plasma levels of indoxyl sulfate in chronic kidney disease patients on hemodialysis?
abstract: BACKGROUND
  Gut microbiota is involved in generation of uremic toxins in chronic kidney disease (CKD) patients on hemodialysis (HD), like indoxyl sulfate (IS) that is originated from tryptophan amino acid fermentation.
  
  
  OBJECTIVE
  To evaluate the tryptophan intake by chronic renal failure patients on HD and its possible relationship with IS plasma levels.
  
  
  METHODS
  Participated of the study 46 patients with CKD on HD regular program (56.5% men; 52.7 ± 10.3 years; 63 (32.2-118.2) months on HD; BMI 25.6 ± 4.9 kg/m2). The tryptophan intake was evaluated by a 24-hours dietary recall (R-24h) performed on 3 different days. Routine biochemical tests and anthropometric measurements were evaluated. IS plasma levels were determined by High Performance Liquid Chromatography (HPLC) with fluorescent detection and the interleukin-6 (IL-6) plasma levels by immunoenzymatic method (ELISA, Enzyme Linked Immunosorbent Assay).
  
  
  RESULTS
  The average of tryptophan intake was according to recommendation, but IS plasma levels (35.0 ± 11.9 mg/L) were elevated, however according to the EUTox values for uremic individuals. There was no correlation between the tryptophan intake and IS plasma levels. However, there was positive correlation between protein intake and tryptophan and variables used to evaluate lean body mass, and moreover, IS levels were positively associated with IL-6 (r = 0.6: p = 0.01).
  
  
  CONCLUSIONS
  The present study suggests that tryptophan dietary intake may not be a determinant factor to IS levels. However, it suggests that gut microbiota may play an important role in systemic inflammation in patients with CKD.
authors.affiliation: Universidade Federal Fluminense, Brazil.
authors.forename: Jessyca Sousa de
authors.initials: JS
authors.lastname: Brito
authors.affiliation: Universidade Federal Fluminense, Brazil.
authors.forename: Natália Alvarenga
authors.initials: NA
authors.lastname: Borges
authors.affiliation: Universidade Federal do Paraná, Brazil.
authors.forename: Carla Juliana Ribeiro
authors.initials: CJ
authors.lastname: Dolenga
authors.affiliation: Universidade Federal Fluminense, Brazil.
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Carraro-Eduardo
authors.affiliation: Universidade Federal do Paraná, Brazil.
authors.forename: Lia Sumie
authors.initials: LS
authors.lastname: Nakao
authors.affiliation: Universidade Federal Fluminense, Brazil.
authors.forename: Denise
authors.initials: D
authors.lastname: Mafra
mesh_terms: D003430:Cross-Sectional Studies; D004032:Diet; D005260:Female; D006801:Humans; D007200:Indican / Q000097:blood*; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D014364:Tryptophan / Q000008:administration & dosage*
chemical_list: D014364:Tryptophan; D007200:Indican