Vitamin D has been an exceedingly popular topic in the media over the past few years. Despite its frequent mention, however, many people fail to get their vitamin D levels checked because they erroneously think they can't possibly be deficient as they get plenty of exposure to sunlight.
It is important to note that exposure to sunlight is not an accurate means of predicting vitamin D levels. In fact, there are no clinical signs or symptoms which can consistently or reliably indicate a deficiency status. The best way to determine vitamin D levels is via blood. A simple blood test will determine the amount of vitamin D, also referred to as 25(OH) D* or calcidiol that is present in your blood serum. Doctors and labs vary on what they consider to be a 'normal' vitamin D level with most labs currently using a result of below 30 ng/mL (75nmol/L) as an indication of deficiency status. Many practitioners are not familiar with the differences between normal and physiologically ideal levels though, and might overlook sub clinical results or alternately, prescribe inferior forms of vitamin D. In any event, you should request a copy of your lab results so you can track your vitamin D levels should you decide to supplement your diet.
One benefit of the additional media attention vitamin D has drawn, is that the costs of testing have decreased significantly. In fact, most insurance companies cover testing, and it can be ordered as a stand-alone test, or in addition to other tests for little additional cost. For uninsured patients, vitamin D testing usually ranges from $60-$100, with many labs offering it for less especially when combined with other tests.
*Make sure that your doctor orders the correct test. An alternative vitamin D test, the 1,25-dihydroxyvitamin D exists, but this is not an accurate measure of stored vitamin D levels.