title: Plasma pteridine concentrations in patients with chronic renal failure.
abstract: BACKGROUND
  Pteridine metabolism is impaired in the uraemic state. This may affect cardiovascular function and contribute to malnutrition. We wished to clarify further the impact of impaired pteridine metabolism.
  
  
  METHODS
  Using the HPLC method, the plasma concentrations of endogenous pteridines were determined in 64 patients with chronic renal failure (33 on intermittent haemodialysis (HD) treatment vs 31 not yet on renal replacement therapy), and in 18 healthy controls. The patients were classified into three groups on the basis of creatinine clearance (Ccr): group (a), Ccr >60 ml/min; group (b), Ccr=10-60 ml/min; group (c), all patients receiving HD.
  
  
  RESULTS
  Total neopterin (NP) and biopterin (BP) levels and the NP/BP ratio (a biomarker for macrophage activity) were significantly higher, whereas tetrahydrobiopterin (BH(4))/dihydrobiopterin (BH(2)) ratio (a biomarker for nitric oxide synthase and phenylalanine hydroxylase activities) was significantly lower in group (c) (118.9+/-11.7 ng/ml, 18.8+/-1.2 ng/ml, 6.79+/-0.53, and 0.26+/-0.06) than in healthy subjects (5.17+/-0.29 ng/ml, 2.83+/-0.19 ng/ml, 1.92+/-0.13, and 1.15+/-0.11; P<0.01). These significant differences were also observed between control and group (b) (12.4+/-2.20 ng/ml, 4.48+/-0.36 ng/ml, 2.81+/-0.48, and 0.74+/-0.08; P<0.01). In groups (a) and (b), significant negative correlations were found between Ccr and the total NP level (r=-0.663, P<0.01), the total BP level (r=-0.492, P<0.01), the BH(2) level (r=-0.677, P<0.01), and the NP/BP ratio (r=-0.493, P<0.01). Conversely, significant positive correlations were found between Ccr and the BH(4)/BH(2) ratio (r=0.602, P<0.01).
  
  
  CONCLUSIONS
  The reduction of quinoid-type BH(2) to BH(4) is modified in patients with advanced chronic renal failure, before and after the initiation of regular HD treatment. These metabolic alterations may play a role in the impaired macrophage, endothelial constitutive nitric oxide synthase, or phenylalanine hydroxylase (PH) activities observed in such patients.
authors.affiliation: The Division of Nephrology and Hypertension, Jikei University School of Medicine, Tokyo, Japan. keitaro@mrj.biglobe.ne.jp
authors.forename: Keitaro
authors.initials: K
authors.lastname: Yokoyama
authors.forename: Masamich
authors.initials: M
authors.lastname: Tajima
authors.forename: Hiraku
authors.initials: H
authors.lastname: Yoshida
authors.forename: Masaaki
authors.initials: M
authors.lastname: Nakayama
authors.forename: Goro
authors.initials: G
authors.lastname: Tokutome
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakagami
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Hosoya
mesh_terms: D015415:Biomarkers / Q000097:blood; D001708:Biopterins / Q000097:blood; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000503:physiopathology / Q000628:therapy; D019798:Neopterin / Q000097:blood; D011621:Pteridines / Q000097:blood*; D012016:Reference Values; D012044:Regression Analysis; D006435:Renal Dialysis
chemical_list: D015415:Biomarkers; D011621:Pteridines; D001708:Biopterins; D019798:Neopterin