I work very closely with a risk manager at a hospital and see a necessary requirement for docs to document any and all medically siginificant oberservations in the record. If something happened to a patient that had a relevance to information that was not documented, the docs would be open to suit. THis whole notion that your records are sealed and confidential is a pipe dream, your records may not be open the public but they are certainly far from private. When you sign up for health insurance or life insurance, one of the clauses you sign is giving them permission to review your records if they deem it necessary. Remember that line on the application form that asks you if you are now or have ever done any illegal drugs?
I would definitely not count on a doc to share your confidence and privacy, sure it might happen in rare cases but do not count on it. If you need a liver panel or other tests, go for a physical. YOu can always tell the doc that you are doing LEGAL supplements, there are plenty out there that would justify tests.