4 Best At-Home Vitamin D Tests To Check Your Levels Of The Micronutrient

Vitamin D plays a crucial role in our immunity and the overall health of our bones, gut, and thyroid—but it's also one of the most common nutrient gaps in the world. While we can get vitamin D from certain foods, it's not enough to truly affect our levels of the "sunshine vitamin." 

Instead, one of the main ways we get this beneficial vitamin is from—you guessed it—exposure to sunlight. However the length of time needed to get enough vitamin D differs by person (season, latitude, skin tone, etc.), and it may require partaking in unsafe skin practices to reach the optimal amount. 

Considering how much of our time is spent sitting indoors at a desk or watching Netflix on the couch, it's no surprise that many people are still struggling to hit the recommended vitamin D intake levels of at least 3,000 IU per day (which is still on the low end). 

If you're curious about your own vitamin D levels, you can ask your doctor for a lab biomarker for vitamin D status called the serum total 25-hydroxyvitamin D test, i.e., the 25(OH)D test, to shed some light on the situation. When an appointment with your health care professional isn't an option, an at-home vitamin D test is another way to test your vitamin D levels from the comfort of your home. 

Vitamin D1 is an essential fat-soluble vitamin that acts like a hormone in its active form. The micronutrient plays an important role in various bodily systems and functions, such as the musculoskeletal, immune, neurological, thyroid, endocrine, and cardiovascular systems. 

Along with supporting thyroid health2, it also helps both the innate and adaptive immune systems by promoting white blood cell function3 and aiding the immune system in defending against threats4. It also plays a role in gut health, supporting beneficial gut bacteria and the gut mucosal lining. 

Finally, vitamin D is key to healthy bones and strong muscles. It helps the body absorb calcium, which is essential for bones, and supports the body in maintaining a balance between calcium and phosphorus. 

An at-home vitamin D test checks the level of the circulating form of vitamin D in your blood. This is your serum total 25-hydroxyvitamin D, or 25(OH)D6 level. 

We receive vitamin D (vitamin D2 and vitamin D3) from foods, beverages, sun exposure, and certain supplements. That vitamin D is converted in our liver to 25(OH)D, the biomarker for vitamin D status in your body. You might also see this test referred to as the calcidiol 25-hydroxycholecalciferol test. 

The other type of vitamin D in our bloodstream and acting inside our cells is 1,25-dihydroxyvitamin D, which is the biologically active, hormone-like form. This doubly hydroxylated form of the nutrient is created when 25(OH)D is further converted by our kidneys and targeted tissues for use in the body.

Similar to tests run by your health care provider, at-home tests check the levels of your vitamin D status biomarker, 25(OH)D, using a blood sample. This requires pricking your finger with a lancet to either fill a vial of blood or collecting a sample on a collection card. 

At-home vitamin D tests are typically shipped directly to your home and require you to mail back any samples within a required time frame for accuracy; some options with vial samples may ask for a same-day return to prevent the blood from clotting. 

Sounds easy enough, right? As with any at-home tests, there are pros and cons to testing vitamin D at home versus in a lab or at a doctor's office.

The first advantage, of course, is ease. "One of the benefits of at-home testing is that you can take the test when it's convenient for you," explains Bonney. "Even if your doctor doesn't feel it's medically necessary to have this test done, with an at-home test you can still get the data to supplement as warranted."

However, it's important to feel supported in understanding your results, which will vary from company to company. "Like any other lab testing, you'll get a reference range, which doesn't tell you what optimal levels are," says Bonney. "These ranges are typically based on what most people are, not what they should be. Doing the test under the guidance of a physician who is focused on making sure you have the right amount of vitamin D is helpful to guide what your dosage of supplementation should be."

It's estimated that 50% of people globally8 have insufficient levels of vitamin D, which are measured in nanograms per milliliter (ng/ml) clinically or sometimes referred to in nanomoles per liter (nmol/l) in research literature.

The Endocrine Society9 defines vitamin D deficiency as the level of 25-hydroxyvitamin (25(OH)D) of less than 20 ng/ml, and vitamin D insufficiency as a 25(OH)D result of less than 30 ng/ml. In other words, these are the baseline cutoffs for avoiding insufficiency and thus, numbers to avoid. Indeed, many health care experts and much scientific research push for levels closer to 50 ng/ml to support bone health, immunity, and whole-body health. 

For example, the Endocrine Society recommends a preferred range of 40 to 60 ng/ml; founder and director of the Anti-Aging & Longevity Center of Philadelphia Seema Bonney, M.D., recommends an optimal range of 55 to 60 ng/ml given the importance of the micronutrient—and she's not the only one. 

Board-certified endocrinologist Brittany Henderson, M.D., previously told mbg that the common 30 ng/ml baseline actually leaves clients underserved, and she personally recommends a higher level.

According to Bonney, for most people, vitamin D testing through a lab would be covered by insurance with the correct ICD-10 code(s) submitted by your health care partner. "But these at-home tests are not," she says. "And if your [at-home] levels are abnormal, this would warrant having them rechecked in a lab setting with proper phlebotomy" and an expert clinical opinion once the result comes in. 

According to our expert, yes. But Bonney warns that the main variable to watch out for is you.

"In general, [at-home] vitamin D tests may be as accurate as lab tests done by phlebotomy, but they do need to be performed correctly," she explains. "This means washing your hands with soap and water (as per the CDC) to remove residue like lotions that can affect the results. It's also vital that you produce a blood drop sufficient to fill the testing strip; otherwise, you'll have an insufficient sample." 

Other possible variables include waiting too long before the blood sample is sent off and assayed for results, as well as testing method errors at the lab completing the assay, according to mindbodygreen's vice president of scientific affairs Ashley Jordan Ferira, Ph.D., RDN. 

From promoting strong bones and a healthy immune system to enhancing your sleep quality, vitamin D is a crucial nutrient that about half of the global population8 does not get enough of without proper vitamin D supplementation.