Effect of Paricalcitol on Endothelial Function in Chronic Kidney Disease (CKD) Patients (the PENNY Study)

Primary objective: Test the hypothesis that Paricalcitol, an active form of vitamin D improves endothelial function in stage 3-4 chronic kidney disease (CKD) patients.

Secondary analysis: Study the relationship between endothelial function and plasma/serum and genetic biomarkers of bone mineral disorders in CKD (BMD-CKD) and renin angiotensin-aldosteron system (RAS) (angiotensin II and plasma renin activity).

Background:

Endothelial function is altered in patients with CKD. Factors responsible for disturbed endothelium-dependent vasodilatation in CKD include reduced bioactivity of the nitric oxide (NO) pathway with decreased endothelial NO synthase (NOS) activity or inhibition via accumulation of endogenous inhibitors. In patients with CKD and in those on dialysis serum 25(OH)D3 and 1,25(OH)2D3 levels are associated with FMD. Vitamin D receptors and 1 -hydroxylase activity are present in endothelial and vascular smooth muscle cells and 1,25(OH)2D3 stimulates vascular endothelial growth factor and prostacyclin production by vascular smooth muscle cells. These biological observations may have clinical implications because paricalcitol treatment predicts longer survival in ESRD patients and very recent data link vitamin D to progression to ESRD in patients with stage 3-5 CKD. Furthermore, a previous study by us has shown that the BMSI polymorphism of the vitamin D receptor gene is associated with LVH and LVH progression in ESRD patients.

Study population: Patients with stage 3-4 CKD of both sexes in the age range 18-80 years. Patients taking vitamin D supplements, with abnormal liver function tests, symptomatic cardiovascular disease, diabetes or cancer and those whose medications changed during the study were excluded.