More and more I am coming across doctors and nutritionists who are recommending routing testing for vitamin D levels. At a cost of 50 to 200 dollars per vitamin D test, and repeated 3 or 4 times a year, it is unimaginable for me to spend a few hundred dollars of precious health care dollars on testing for one vitamin level. Don't people who advocate such testing recognize how much we, as a nation, already overspend on healthcare? Why not just pay a few dollars a year taking vitamin D pills instead of doing the testing. Do people test their levels of vitamin C, B vitamins, and vitamin E before they take a multivitamin? Do people test their levels of omega-3 fatty acids before taking fish oil pills? If the logic proposed by testing promoters is that we should know our test results before taking any supplement then why not spend thousands of dollars a year testing for every possible vitamin, mineral, hormone, neurotransmitter, fatty acids, lipids, inflammatory markers, amino acids, immune system function levels in the body? Even if we know the results at a specific point in time, there are few accepted guidelines regarding the dosage of supplementation based on such test results, and different doctor will recommend different supplementation dosages.
Mind you, I am not against all testing. When done appropriately it can give a great deal of information about the patient and guide treatment in the proper direction. I just think that if a doctor spends more time doing a thorough history, review of symptoms, dietary history, sleep patterns, psychological stresses, and a thorough physical exam, he or she can often be much more selective in choosing the appropriate testing. The art of the full history and physical has been somewhat lost and replaced by the quick, easy and mindless referral to testing. In the case of vitamin D, if a doctor reviews the patient's pattern of sun exposure throughout the year and the types of foods a person eats, this alone will go a long way into determining the amount of the vitamin to suggest taking: from none to 2000, or perhaps in rare cases 3000, units a day.
There is a website that I suggest you and your doctor refer to that evaluates the scientific basis of what screening tests are appropriate at different decades of life. I value the information, caution and thought that has gone into making the recommendations: See http://www.ahrq.gov/clinic/uspstf/uspstopics.htm. Not all the recommendations will eventually turn out to be right, but this site is a good start.