I recently went to hear a local rheumatologist give a presentation to a group in my area. He was very interesting and talked a lot about
Vit D. When they first changed the reference ranges (6-7 years ago?) he called the doctor who conducted the studies that provided the new range. He asked this doctor where he wanted his patients Vit D levels and he said at least 60! This rheumatologist has gone further and believes his patients should go into the winter with levels above 65.
I asked him about my "normal" level of 38 in the summer and he said I was severely deficient. He also believes a person needs to take high doses for over a year before they switch to a maintenance dose. That your body needs to build up its reserves in your muscles before it can maintain an adequate level. When he put his patients on 50,000 units a week for 6 - 12 weeks their levels would rise, but immediately plunge back down on the maintenance dose.
He said low levels cause balance issues, joint pain, muscle pain and many others. He believes Vit D is just one piece of the puzzle and is not a cure all, but if you bring a lot of these levels (B,D,etc) into range you can improve symptoms.
Just thought I would pass on this info! 