Vitamin D - regular in dialysis patients

I recently started working in a new center where we do Vitamin D levels, specifically, 25(OH)D3 levels. Some of the nephrologists are starting hemodialysis patients on regular plain Vitamin D 1000 IU po daily when these levels are low. They are apparently doing this based on the study that came out regarding Vitamin D reducing cancer risk (although this study was highly critisized) and also from the following paper:
25(OH)Vitamin D3 in patients with chronic kidney disease and those on dialysis: rediscovering its importance
Int Urol Nephrol (2006) 38:323-329
The later paper discusses how many other tissues in the body (other than the kidney) express 1-hydroxylase and synthesize 1,25(OH)2D3 locally. As KDOQI does not address the use of regular Vitamin D in dialysis patients, I am unsure how to interpret PTH levels and if regular Vitamin D would even affect PTH to any extent. Does anyone else have dialysis patients who take regular Vitamin D or know of any evidence for this practice? I even have some patients on both regular Vitamin D and active Vitamin D. Your input is appreciated.