Vitamin D deficiency is not associated with increased oxidative stress in chronic kidney disease pre-dialysis patients

Abstract

Introduction: The progressive decline in 25-hydroxyvitamin D [25(OH)D] in chronic kidney disease (CKD) limits the kidney ability of synthesizing the vitamin. Vitamin D deficiency as defined by KDIGO (25(OH)D <20 ng/mL) is prevalent in CKD patients and associated to oxidative stress (OS). We studied a possible association between vitamin D deficiency and OS in pre-dialysis patients. Methods: A cross-sectional study with 206 CKD patients was carried out. Laboratory tests for 25(OH)D, 1,25(OH)2D, inflammatory markers, and OS were added to routine tests including creatinine, albumin, calcium, phosphorus, alkaline phosphatase, iPTH, glucose, hemoglobin, uric acid, total cholesterol, LDL, HDL, and triglycerides. Results: Vitamin D deficiency was present in 55 CKD patients and normal vitamin D levels were seen in 149 patients. There was a significant association between vitamin D and estimated glomerular filtration rate (eGRF). Homocysteine levels were best predicted by eGRF, sex, and age; high sensitivity C-reactive protein (hsCRP) by staging and BMI; nitric oxide metabolites (NOx) were increased in late disease; leptin was influenced by BMI and higher in women than man; and adiponectin levels were higher in women. Conclusions: OS biomarkers were not correlated with vitamin D deficiency but increased NOx were seen in stages 4-5 CKD patients. Even though a relatively large number of CKD patients was included and a broad number of OS and inflammatory biomarkers were used in this studied we failed to find an association between vitamin D levels and eGRF. More studies are needed to evaluate the influence of vitamin D status in OS in pre-dialysis CKD patients.

Vitamin D and chronic kidney disease: an uneasy relationship

“…The prevalence of vitamin D deficiency, defined as serum levels of 25(OH)-vitamin D below 20 ng/mL, in the study population was 27% (55/204) and it was inversely correlated with renal function. The multivariate analyses could not demonstrate any significant effect of vitamin D on the levels of inflammatory and oxidative stress biomarkers 5 . Contrarily, CKD stages were correlated with oxidative stress.…”

“…Therefore, it could be somewhat expected that (i) the superiority of one marker, in this case serum levels of vitamin D, over the others could not be demonstrated and that (ii) renal function, as a global marker of uremia, would explain the greater levels of inflammatory and oxidative stress biomarkers seen in these patients. However, the small sample size, stated as a study limitation by the authors 5 , may have precluded a more robust statistical analysis.…”

“…Contrarily, CKD stages were correlated with oxidative stress. The authors concluded that vitamin D deficiency might not play a role in the increased oxidative stress state commonly seen in pre-dialysis CKD patients 5 .…”

“…In the study published in this issue of the BJN, Matsumoto et al . investigated the association between deficiency of 25-hydroxyvitamin D and inflammatory and oxidative stress in a cohort of pre-dialysis CKD patients 5 . The study included 206 pre-dialysis CKD patients who were not using vitamin D supplementation.…”