What I know came from the mega dosing book and the Internet. The blood level I achieved with 25,000iu's of 80ng/mg falls into the "new normal" range. I get testosterone pellet implants every 3-4 months so I always have my Vitamin D levels tested at the same time. Like I said, I don't really feel any different except I didn't get sick this past winter. The 50,000iu dose took me to 130ng/ml and that seemed too high so I backed it down to 25,000iu's.