title: Plasma kynurenic acid/tryptophan ratio: a sensitive and reliable biomarker for the assessment of renal function.
abstract: BACKGROUND
  Decreased tryptophan (TRP) and increased kynurenine (KYN) and kynurenic acid (KYNA) in blood have been reported in patients and experimental animals with renal diseases. We investigated if these compounds could be used as new biomarkers for the assessment of renal function.
  
  
  METHODS
  Eighty hospitalized hypertensive patients (20 with chronic kidney disease (CKD), and other 60 were considered as control) were enrolled for the investigation. Plasma TRP, KYN, and KYNA were determined by high-performance liquid chromatography. Change rate (CR) was employed to evaluate the sensitivity of the parameters of renal function.
  
  
  RESULTS
  CR of plasma KYNA/TRP ratio (+103%) was much higher than the CRs of blood urea nitrogen (+44%), serum creatinine (+56%) and estimated glomerular filtration rate (-35%). Plasma KYNA/TRP ratio was in close relationship with blood urea nitrogen (r = 0.622), serum creatinine (r = 0.797), urine micro-albumin/24-h (r = 0.518) and estimated glomerular filtration rate (r = -0.662), respectively, with all p-values <0.001.
  
  
  CONCLUSIONS
  Plasma KYNA/TRP ratio was sensitive and reliable to indicate renal function and could be used as a new biomarker to assess the risk or presence of kidney disease.
authors: Shanghai Key Laboratory of Vascular Biology, Ruijin Hospital and Shanghai Institute of Hypertension, Shanghai Jiao Tong University School of Medicine, Shanghai, China. jzhao021@yahoo.com
authors: Jianxing
authors: J
authors: Zhao
mesh_terms: D000328:Adult; D000368:Aged; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000150:complications; D007677:Kidney Function Tests; D007736:Kynurenic Acid / Q000097:blood*; D007737:Kynurenine / Q000097:blood*; D008297:Male; D008875:Middle Aged; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000150:complications; D014364:Tryptophan / Q000097:blood*
chemical_list: D007737:Kynurenine; D014364:Tryptophan; D007736:Kynurenic Acid