David, don't quote me on this because I might get it wrong, but at a glance I seem to remember that my level was 17 (17 what exactly, I'm not sure), and he said that I should be at least at 30. Keep in mind that I like my primary care doctor, he's a good guy, but this was my first physical and I didn't know what to ask. He just said to start with 2000IU daily.
With that said, I have a follow-up with him in 2 months, and I'm waiting for results on another blood test that I had done with the GI (iron and B12). When you say "regular testing," how often are we talking? Once a month? More/less?
Beach, thanks for that link. Maybe I should have picked up gels instead of tablets. Hmmm.