I haven't learned about vitamin D conversion yet, so I'm no help there...
Sugar is supposed to affect blood calcium, per Melvin Page, but I haven't been able to track down any studies confirming that. Umm... vit K puts calcium into bones, maybe a deficiency would leave it in the blood? the vitaminK yahoo group has a bunch of people dealing with high blood calcium levels...
The other reasons that like to pop up (cause they're easy) are hormone secreting tumors, but it seems like that would be more of an acute issue?
Maybe I should check out the yahoo group. I wonder what would cause low vitamin K... I know I did research on it not long ago but I've forgotten already.
ETA: But if I had low K, I wouldn't have been growing calcifications would I?