Am I vitamin D deficient?

Are you vitamin D deficient? Find out with ZRT's in-home vitamin D test kit.

This may be one of the most important questions you could ever ask yourself...and also one of the easiest to answer.

If you do not receive proper sun exposure and/or supplement with adequate amounts of vitamin D3, odds are you are vitamin D deficient. The only way to know for sure is to have your blood vitamin D levels tested.

A vitamin D test will tell you how much of the storage form of vitamin D, known as 25(OH)D or calcidiol, is present in your blood serum.

Testing vitamin D levels

How do I get tested?

There are two ways to obtain a vitamin D test:

  1. Ask your doctor for a 25-hydroxyvitamin D, or 25(OH)D, test. One may also refer to it simply as a “vitamin D test." In the past, doctors have been known to order a 1,25-dihydroxyvitamin D test. This is the wrong test as it cannot determine vitamin D deficiency. Make sure your doctor orders the correct test.
  2. Purchase an in-home test kit and test your levels yourself.

Which is best for me?

Testing blood levels is the only way to know for sure if one is getting enough vitamin D.

If you have medical insurance and your insurance will pay for your vitamin D test, the money you will save is a good reason to have your doctor perform the test. Those who have hemophilia, who use blood thinners, or who do not feel comfortable performing the test themselves might also choose to have their physician perform the test.

If having a doctor test your vitamin D levels, again, make sure the correct test is ordered - a 25-hydroxyvitamin D test. In addition, many doctors still consider a result of 30 ng/mL (75 nmol/L) to be sufficient when studies indicate otherwise. For this reason, it is a good idea to ask for the exact number value of the results or a hardcopy. Results conveyed by use of the words "normal," "within range," or similar wording might still be inadequate.

If you do not have medical insurance, or your insurance will not pay for your vitamin D test, a home test kit would probably be the least-expensive option. Besides low cost, additional benefits to using an in-home test are that you are in control of when, and how often, you test as well as what you do with the results.

In-home vitamin D test

Vitamin D Council has partnered with ZRT Laboratory to make available an inexpensive, easy to use, in-home vitamin D testing kit. (Disclosure: A portion of the proceeds from the sale of each test will be donated to the Vitamin D Council by ZRT.)

What to expect

ZRT’s Vitamin D Kit is suitable for use with adults and children. When using the ZRT test kit you will find the procedure to be both simple and straightforward:

  1. Purchase the test kit from ZRT. ZRT will ship the test kit straight to you.
  2. Once the test kit is received, and when ready, follow the instructions. The test is simply a finger prick with a lancet, with the samples (blood drops) to be placed on the included blotter paper.
  3. The form included in the test kit does not have to be filled out in full. The only information required is your name and address. Notating amount of daily supplemented vitamin D is helpful.
  4. After you have collected your samples (minimum of two good-sized drops), return the samples to ZRT using the postage-paid envelope provided.
  5. No additional fee is required for domestic orders -- the test results are included in the initial cost.

For further information please see ZRT’s website.

Interpreting results

ZRT test results are given in nanograms per milliliter (ng/mL) and reflect total serum 25(OH)D.

Total serum 25(OH)D is the total amount of vitamin D in your blood, both vitamin D3 and vitamin D2:

Total 25(OH)D = 25(OH)D3 + 25(OH)D2

Since vitamin D2 is not naturally present in the human body, if you do not use anything that contains vitamin D2 your results will only show vitamin D3. This is fine, since vitamin D3 is the preferred form.

Serum level ranges

For optimum health, vitamin D blood levels should be around 50-80 ng/mL (125-200 nmol/L).

ZRT lists a lab reference range for vitamin D at 32-100 ng/mL. Reference ranges represent the range of values that the majority of the population will fall between and are not indicative of values which would be considered optimal.

Studies indicate that for proper health, serum vitamin D levels should be a minimum of 50 ng/mL (125 nmol/L), with optimal levels falling between 50-80 ng/mL (125-200 nmol/L). These values apply to both children and adults.

How accurate is ZRT's vitamin D test?

The Vitamin D Council has verified that results obtained by ZRT are accurate and correspond very well to the results given by both LabCorp and DiaSorin RIA, whose method is considered the “Gold Standard” in vitamin D testing.

Page last edited: 21 September 2012