title: Decreased plasma level of vitamin C in chronic kidney disease: comparison between diabetic and non-diabetic patients.
abstract: BACKGROUND
  A decreased plasma level of vitamin C has been reported to be associated with an increased risk of cardiovascular morbidity and mortality. Here, we sought to determine the vitamin C status of patients with chronic kidney disease and the pathophysiological role of vitamin C in these patients.
  
  
  METHODS
  We studied 58 patients and evaluated the relationship between renal function and plasma vitamin C concentration, as well as the effect of diabetes on this relationship. Endothelium-dependent flow-mediated dilation of brachial artery was measured to assess the endothelial function. Serum malondialdehyde low-density lipoprotein was measured as a marker for oxidative stress.
  
  
  RESULTS
  Plasma vitamin C concentration had a positive linear relationship with eGFR in both diabetic and non-diabetic patients (P = 0.006 and P = 0.004, respectively). When vitamin C concentration and eGFR relationships were compared in the two groups, vitamin C concentration was significantly lower in diabetic patients at every eGFR (P = 0.006). Flow-mediated vasodilatation of the brachial artery was positively correlated with vitamin C concentration in non-diabetic patients (P = 0.047) but not in diabetic patients. There was a negative correlation between serum malondialdehyde low-density lipoprotein and vitamin C concentration in non-diabetic patients (P = 0.044) but not in diabetic patients.
  
  
  CONCLUSIONS
  Renal dysfunction was associated with a decrease in plasma vitamin C level. Moreover, decreased vitamin C may cause endothelial dysfunction via an increase in oxidative stress in non-diabetic chronic kidney disease patients.
authors.affiliation: Second Department of Internal Medicine, Kansai Medical University, Hirakata City, Osaka, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Takahashi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Morimoto
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Okigaki
authors.forename: Maiko
authors.initials: M
authors.lastname: Seo
authors.forename: Kazunori
authors.initials: K
authors.lastname: Someya
authors.forename: Tatsuyori
authors.initials: T
authors.lastname: Morita
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Matsubara
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Sugiura
authors.forename: Toshiji
authors.initials: T
authors.lastname: Iwasaka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000097:blood*; D001206:Ascorbic Acid Deficiency / Q000150:complications*; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000209:etiology*
chemical_list: D000975:Antioxidants; D001205:Ascorbic Acid