My d3 is very low, I took a prescription high dose for a few weeks then switched to otc high potency d3..4,000iu's i think. My labs have been good since.
So, I'm helping my sister in law out after a very bad illness. She is far from recovered but home with visiting nurses, bath aid, home PT and OT etc.
I posted my blood results a few pages back but I don't know if they tested that specifically or not.
I'm really starting to dig these guys, I may buy their album next week.