i am nowhere near that. but i've described my issues before with this state medical system and unavailability OTC. doctor won't test more than 1ce or 2ce a year and prescribes tiny amounts. when i started taking it, at my own request, i was at 6 or 7.

and he prescribed 750iu a day, taken in a single cumulative dose, 1ce a week. i don't recall if the next test was in the teens or the twenties - i think in the teens.
he did not indicate to take more, but having tested a couple times i feel very safe taking 1,500iu/day now, grouped in 2 biweekly dosings. (i wouldn't exceed 10,000iu on a single day even if i don't take a dose every day at the moment.)
i hope to be over 30 the next test. if not, i'll go up again. i figure i may need about 5000iu a day... i want to get to a level of about 50.
i don't get sun during summer or winter so i don't have to worry about that. some supplements i take occasionally contain vit D, but in such small quantities as to be negligible against 5000iu/daily.
~ waves ~