Vitamin D Test


At-home collection kit. Meaningful insights. Personalized plan.

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A low level of vitamin D is linked to various health risks. This at-home blood test will provide health insights by measuring your level of vitamin D. Results include a personalized health plan.

Test taker must be 18+ and reside in the U.S.

At-home tests are not permitted for use in:

  • Armed Forces Americas
  • Armed Forces Europe
  • Armed Forces Pacific
  • American Samoa
  • Maryland
  • Northern Mariana Islands
  • New Jersey
  • New York
  • Rhode Island
  • United States Minor Outlying Islands

You should take this test if you

  • Do not get daily sun exposure or live in a northern latitude
  • Do not consume adequate vitamin D
  • Follow a strict vegan diet
  • Have darker-pigmented skin
  • Have issues with small intestine absorption or kidney function
  • Are an athlete
  • Are overweight or obese
  • Are elderly



It is estimated that 42 percent of U.S. adults have a sub-optimal vitamin D level.

Vitamin D, which is measured as 25-hydroxyvitamin D (25OH-D), is a fat-soluble vitamin that is responsible for multiple biological processes. Vitamin D, which has always been known for its capacity to support the absorption of calcium, has more recently been found to support immune function, a healthy inflammatory response, and muscle function. A low vitamin D level is associated with a higher risk for various chronic health concerns, including heart disease and diabetes.

Unlike vitamins that must be acquired from outside sources, humans can make vitamin D in their skin with adequate exposure to sunlight. Because we do not get as much sunlight as our ancestors, and because we might not consume adequate dietary sources of vitamin D, many individuals are at risk for too low of a level. A too high level of vitamin D can also occur, but this is much less common and is nearly always associated with excessive supplementation. Thorne's Vitamin D Test measures total vitamin D, which includes the two common forms of vitamin D ‐ D2 (25OH-D2) and D3 (25OH-D3). 25OH-D3 includes the amount derived from internal production, as well as the amount derived from diet and supplementation; whereas, 25OH-D2 reflects only what is acquired in the diet or from supplementation. Together, these two biomarkers make up an individual's total 25OH-D level.

A healthy vitamin D level can be crucial for optimal athletic performance, bone repair after exercise or injury, normal muscle function, healthy immune function, and cardiovascular health. Therefore, it is widely accepted that athletes, compared to non-athletes, should strive to maintain a higher than sufficient level of vitamin D.

Potential symptoms of low vitamin D

Although having a low level of vitamin D is often asymptomatic, you might experience:

  • More frequent infections
  • Fatigue
  • Muscle or bone discomfort
  • Depressed mood

If you have any of the following symptoms that are, or can be, associated with a vitamin D deficiency, then you should consult with your health-care practitioner:

  • Muscle spasms and twitching (which can be anywhere but are more common in the face and around the mouth or eyes)
  • Generalized weakness
  • Loss of balance/falling
  • Severe bone and joint pain – hip pain is most common
  • Unexplained fracture
  • An onset of seizures
  • Abnormal heart rate or rhythm
  • High blood pressure

Potential symptoms of high vitamin D

Although having a vitamin D level that is too high can be asymptomatic, with a very high level (usually a result of excess calcium absorption) you could experience:

  • Anorexia/loss of appetite
  • Vomiting
  • Diarrhea and/or constipation
  • Excessive thirst, dry mouth
  • Frequent urination
  • Fatigue
  • Dizziness
  • Muscle cramping/pain/twitching
  • Bone pain
  • Nerve pain (neuropathy)
  • Kidney stones
  • Confusion and weakness
  • Chest pain, irregular heart beat
  • Elevated blood pressure
  • Headaches
  • Cough, shortness of breath

If you suspect you might have an excess level of vitamin D (which only occurs with excessive supplementation and is very uncommon), then you should consult with your health-care practitioner.Test

How it works

Three steps. It's simple.

Purchase test

Skip the waiting room and lab visit. Get a test delivered to your doorstep.

Collect and send

Collect bio samples at home, then drop free return envelope in any mailbox.

View and plan

Review your results and recommendations on a desktop or mobile device within 3-5 days.

What the tests tell you

Biomarker values

Simple visualization of your biomarker results over time, plus detailed descriptions of each biomarker for an easy interpretation of your overall health.

Health analysis

Insights based on your results help you identify potential health risks or areas of improvement.

Personalized plan

Access your diet, activity, and supplement plan anytime, anywhere through the Thorne dashboard. Recommendations are generated from our medically-supervised algorithms based on your unique test results.

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