NDT Advance Access originally published online on December 19, 2005
Nephrology Dialysis Transplantation 2006 21(6):1735-1736; doi:10.1093/ndt/gfk003
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Is oxidative stress implicated in high bone turnover in end-stage renal disease (ESRD)?
Email: gtripepi{at}ibim.cnr.itSir,
End stage renal disease (ESRD) is a condition in which oxidative stress is much enhanced and implicated in a variety of uremic complications [1,2]. Oxidative stress influences bone turnover [3,4] and in theory may also play a role in bone disease in ESRD. To explore this hypothesis, we investigated the relationship between an oxidative stress marker such as oxidized LDL (ox-LDL) and a specific biomarker of bone turnover [5] alkaline phosphatase (AlkPhos) in the cardiovascular risk extended evaluation in dialysis (CREED) database [6]. We excluded from the study all conditions that may independently influence bone turnover (diabetes, parathyroidectomy, treatment with aluminium hydroxide or beta-blockers). Thus, from an original cohort of 283 individuals, 161 dialysis patients (age 62±16 years, 93 males and 68 females) were included in this analysis.
As shown in Figure 1, there was a graded increase in serum levels of AlkPhos across tertiles of ox-LDL and this association also held true when ox-LDL and AlkPhos were analysed as continuous variables (r = 0.31, P<0.001). Such an association remained highly significant (ß = 0.21, P = 0.005) even after adjustment for a series of potential confounders such as age, sex, duration of dialysis, treatment modality, use of calcium carbonate or calcium acetate, serum calcium and phosphate, body mass index and serum C-reactive protein.
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In patients with ESRD, serum levels of AlkPhos are directly related to ox-LDL and this association is independent of a series of potential confounders. We believe that our observation is hypothesis-generating in that it suggests that the effects of oxidative stress in ESRD may also encompass bone disease. Further studies, considering more refined markers of bone turnover and of oxidative stress and interventions in experimental models, represent useful areas to further explore the link between bone turnover and oxidative stress in ESRD.
Conflict of interest statement. No conflict of interest is related to this letter.
CNR-IBIM, Clinical Epidemiology and Physiopathology of Renal Disease and Hypertension Reggio Calabria Italy
References
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