Arterial stiffness and 25-hydroxyvitamin D levels in chronic kidney disease patients.

Objective: Arterial stiffness refers to arterial wall rigidity, particularly developing in central vessels. Arterial stiffness increases in early stage chronic kidney disease (CKD), and it is a strong predictor of cardiovascular and all cause mortality. Vitamin D has beneficial effects on blood pressure, vascular endothelial function and arterial stiffness. 25-hydroxyvitamin D (25(OH)D) deficiency is quite common worldwide and in the CKD population. We aimed to evaluate the prevalence of 25(OH)D deficiency and its relation with arterial stiffness in CKD.

Method: Our study included 101 patients (51 male, 50 female), with stages 3B-5 CKD not on dialysis. A single-cuff arteriograph device (Mobil-O-Graph) was used to evaluate arterial stiffness parameters of pulse wave velocity (PWV) and augmentation index (Alx@75). The patients were divided into two groups: group I vitamin D non-deficient [25(OH)D > 15 ng/mL] and group II vitamin D deficient [25(OH)D ≤ 15 ng/mL].

Results: Overall, the mean 25(OH)D level was 14.1±7.9 ng/mL and 70 patients (69.4%) were vitamin D deficient. The mean Alx@75 value was significantly higher in group II (28.6±10.8% vs. 23.3±13.5%, p=0.038). PWV was higher in group II, but the difference was not significant. Group II exhibited significantly lower serum albumin (p<0.001), hemoglobin (p=0.005), calcium (p=0.041) and estimated glomerular filtration rate (eGFR) (p=0.041), but significantly higher 24-hour proteinuria (p=0.011) and more females (p=0.006). Vitamin D was negatively correlated with Alx@75 augmentation pressure, parathyroid hormone, proteinuria and body mass index, and positively correlated with albumin, hemoglobin, eGFR, calcium and transferrin. 25(OH)D was independently associated with Alx@75 (beta=-0.469, p=0.001) and albumin (beta=0.447, p=0.002).

Conclusion: In CKD patients 25(OH)D deficiency was common, particularly in females. Level of 25(OH)D was independently associated with Alx@75.