A Randomized Trial of Vitamin D Supplementation on Vascular Function in CKD.

Randomized, 1:1 placebo-controlled trial in adults 18 to 70 years old with non-diabetic chronic kidney disease stage 3 to 4 and vitamin D deficiency, conducted at PGIMER in Chandigarh, India. In the cholecalciferol arm, 58 participants were randomized and 56 completed the final analysis.

Cholecalciferol (native vitamin D) was given orally as 300,000 IU under direct observation at baseline and again 8 weeks later, for a 16-week follow-up. The comparison group received matching placebo.

Cholecalciferol improved endothelial function and arterial stiffness over 16 weeks in vitamin D-deficient, non-diabetic CKD patients. Flow-mediated dilation increased by 5.42% within the cholecalciferol arm, with a between-group mean change difference of 5.49% versus placebo, and pulse wave velocity decreased significantly. Serum 25(OH)D rose by 24.91 ng/mL, while inflammatory and mineral metabolism markers also improved, including significant reductions in IL-6 and parathyroid hormone. The intervention was well tolerated, with no hospitalizations, no serious adverse events, and no severe hypercalcemia.

The trial was relatively small, single-center, and short term, with only 16 weeks of follow-up. Outcomes were mainly surrogate vascular and biomarker endpoints rather than clinical cardiovascular events, and the findings apply only to vitamin D-deficient, non-diabetic CKD stage 3 to 4 patients.