Oxidative Stress and Plasma Concentrations of Coenzyme Q10, α-Tocopherol, and β-Carotene in Patients with a Mild to Moderate Decrease of Kidney Function

Accessible online at: www.karger.com/journals/nef Dear Sir, Oxidative stress (OS) and decreased function of the antioxidant system are apparent in dialysis patients [1] and even in ‘uremic patients’ during the predialysis phase [2, 3]. However, data on OS in predialysis patients with a just mild to moderate kidney function decrease are lacking. We have determined OS plasma concentrations of malondialdehyde (MDA), the parameter of lipid peroxidation, coenzyme Q10 (CoQ10), ·-tocopherol (·-TOC), and ß-carotene (ß-CAR) and performed standard kidney function tests in a group of 55 predialysis patients with mild (creatinine clearance 160 ml/min; n = 21), moderate (n = 25), and severe (creatinine clearance !25 ml/min; n = 9) glomerulonephritis or interstitial nephritis. The reference values were obtained from original procedures and previous studies of our group. The MDA plasma levels were increased even in a group with a mild decrease of the creatinine clearance (table 1), and no further significant MDA increase was apparent with further decreases of the creatinine clearance (r = –0.242, p = 0.078). On the other hand, the CoQ10 concentrations were decreased in patients with mildly decreased creatinine clearance, and no further decreases were apparent with further decreasing kidney function (r = 0.186, p = 0.179). A correlation was found between these two variables (r = 0.327, p = 0.018). The concentrations of ßCAR were in the normal range in patients with a mildly decreased creatinine clearance, but decreased with deteriorating kidney function (r = 0.320, p = 0.030). The ·-TOC plasma concentrations were slightly increased in patients with mildly decreased creatinine clearance, but increased further with the decreasing creatinine clearance (r = –0.364, p = 0.007). Thus, OS develops during the early phase of kidney disease (marker of OS: increased MDA levels). The changes of ·-TOC and ßCAR are opposite: while ·-TOC concentrations increase, ß-CAR concentrations decrease. This basic relationship could be modified by various factors: for instance, the highest values of MDA (p = 0.010) were found in 5 patients treated with prednisone combined with ciclosporin. It could be concluded that OS develops early in patients with kidney disease, probably with pathogenetic significance and the possibility of preventing the progression of kidney impairment. The significance of CoQ10 seems to be of outstanding interest.