Decreased plasma level of vitamin C in chronic kidney disease: comparison between diabetic and non-diabetic patients.
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.
Takahashi
Nobuyuki
N
Second Department of Internal Medicine, Kansai Medical University, Hirakata City, Osaka, Japan.
Morimoto
Satoshi
S
Okigaki
Mitsuhiko
M
Seo
Maiko
M
Someya
Kazunori
K
Morita
Tatsuyori
T
Matsubara
Hiroaki
H
Sugiura
Tetsuro
T
Iwasaka
Toshiji
T
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*
D000975:Antioxidants; D001205:Ascorbic Acid