@cliffdweller - keep up the deep dive into these matters - I do the same and then drive everyone else around me crazy with what I've learned. Thanks for this link!

My conventional Dr prefers my Vit D levels to be at a lower range than my integrative Dr. After much reading, I agree w/my integrative Dr. I find that not taking any of my supplements a day or two prior to a lab draw probably gives a more accurate reading of levels...but who knows???