Well, that is a Catch 22 --because most doctors are still using the RX D2 version which is not adequate.

Even Dr. Oz's program contradicted itself! I have his latest one on D on the D thread in our Vitamin forum.

He started off saying you cannot get D from food. He told one gal to use 60,000 IU monthly of D3 when her level was 7.
Not enough.

He told a moderately low person to use Cod liver oil...which is high in A, and the thinking is that the A will block some D utilization. There is typically 1000IU of D in cod liver oil.

He told a moderately low person, to eat shitake mushrooms to raise her D (remember--- no D3 in food!-- mushrooms have a small amount of the less active D2 in them if they are exposed to light near the end of their growing period).

So even on his own show, he gives confusing advice IMO.
Most medical doctors are the same or worse. He neglected the cofactors (esp magnesium deficiency, and the fact that overweight/obese people need higher doses). He did not explain the differences between the old RX D2--ergocalciferol---and the active D3--cholecalciferol. Very important distinction.

The generally accepted information from specialist MDs is now on this site:
http://www.grassrootshealth.net/

Your goal should be a minimum reading of 50 (in US standard testing) and you should be using D3 to get there. Dr. Oz alluded to it if you watched the charts he showed...but he did not explain how to arrive at the figure quoted. Don't expect most doctors to understand either.

Get tested!