A Vitamin D blood test looks at your levels of 25-hydroxy-vitamin D or 25(OH)D, which is the circulating form of vitamin D used to diagnose whether or not you are deficient in vitamin D. Understanding what level of Vitamin D is in your blood has become an increasingly popular test when wanting to maintain health. For optimum health and normalized vitamin D metabolism, 25(OH)D levels between 50 and 80 ng/mL are recommended by The Vitamin D Council all year round. These levels are believed to be the levels one would obtain if living a more natural life outdoors instead of the indoor city life many of us live today.
Much of what The Vitamin D Council advocate still has to be 'proven' through approved tests or what is termed 'controlled trials". Many such studies are currently being conducted to see if vitamin D really does help prevent or even help treat disease. I certainly would prefer to have my Vitamin D levels up where The Vitamin D Council believe they should be if I were to be living an old fashioned healthy outdoor lifestyle. So, while I wait for the results of these many different controlled trials, I choose to retain my Vitamin D blood levels between 50 and 80 ng/mL.
There is an extremely interesting and comprehensive study being conducted by an organization called Grassroots Health. It doesn't just involve a Vitamin D blood test, it requires that you complete a health based questionnaire and then you have a choice to commit to their program over the following 5 years or just do a once off test. All of this for a really nominal fee too.
By joining them you become part of what they call their "international project to solve the world's Vitamin d deficiency" problems called D*action. Their motivation is the desire to be able to demonstrate the effect that Vitamin D has on many people's health and more specifically, in the prevention of many diseases or health conditions.
If you choose to participate in their 5 year project, you must submit a Vitamin D blood test every 6 months. The test is done specifically for 25-hydroxy vitamin D [25(OH)D serum levels. These tests help not only to assess people's health status while improving their Vitamin D levels, but to track deficiency levels and do something about it. They not only test your blood through two drops of blood on a blood spot card that you send them, but also provide feedback on the results, together with educational material related to your specific results and your target levels. The key investigator behind this is Dr Cedric Garland and the costs involved are:
This is an international study which is expected to involve over 100,000 participants.
Minimal risk is involved in this method of obtaining blood samples for testing 25(OH)D. Most people conduct the test in the privacy of their own home, using a sterile self-loaded lancet provided to puncture your fingertip. Best results are obtained after thorough, sterile washing of your finger. There is no guarantee that you will receive a direct benefit if you agree to participate. However, in my opinion, just knowing what my Vitamin D levels are provides a peace of mind where my general health is concerned, that is invaluable. Also, they point out that another benefit will be that "people in the future may benefit from the information obtained from this research."
As an ambitious international research project, great lengths have been taken to make sure your personal data remains safe and confidential. For any analysis purpose, only an arbitrary number will identify you as a participant.
If you don't want to go to the lengths of joining up with this international study for a Vitamin D blood test, or you query the validity of finger prick blood samples vs blood samples taken via syringe, there are other alternatives:
Having taken the trouble to have your 25 OH Vitamin D tests done, there are 2 different ways to get the results back. One is in nmol/L and the other is in ng/ml. If required to convert one to the other, there is a simple solution - you divide the nmol/L by 2.5 to get ng/ml. Conversely you multiply ng/ml by 2,5 to get the nmol/L. Different countries use different measurements and I also find that in one research article you may find a reference to both, which just confuses me, so I convert them!