The authors of the original paper described their cut-off for Vitamin D deficiency as < 20 ng/dL, which I dutifully copied. However, you are, in fact, correct that the proper unit should be "ng/ml."
I have, therefore, edited this article (even though it conflicts with the original paper).
Thank you for catching this error and calling me on it!
Sincerely,
Robert A. Wascher, MD, FACS
Author, "A Cancer Prevention Guide for the Human Race"
http://twitter.com/mmibooks Issac Perry
Each article of preventative treatment enough to save lives.
