1. 1. Order Your Tests

    Browse from hundreds of tests and select the ones you want.

  2. 2. Visit a Lab

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  3. 3. Get Your Results

    Physician-reviewed lab results are available online within 24-72 hours.

Vitamin D 25-Hydroxy Test (Calcidiol)

This Vitamin D 25-Hydroxy Blood Test, or calcidiol test, measures the amount of vitamin D2 (vitamin D 25-hydroxy or calcidiol) in the blood.

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Test Preparation:
Fasting is required (i.e. no eating or drinking anything besides water for 8 hours prior to testing)
Testing Method:
Blood draw

This Vitamin D 25-Hydroxy Blood Test, or calcidiol test, measures the amount of vitamin D2 (vitamin D 25-hydroxy or calcidiol) in the blood. It is the preferred test to diagnose potential vitamin D deficiencies. Vitamin D deficiencies can lead to more serious conditions including osteomalacia and hypocalcemia and signs include weakness, fatigue, and various aches and pains. Sunlight, fish, and vitamin D milk are excellent sources of vitamin D and are suggested remedies for those needing a vitamin D boost. Pinpoint the source of these symptoms by taking our reliable Vitamin D 25-Hydroxy Test.

How Our Vitamin D 25-Dihydroxy (Calcitriol) Test Works

If you need to take a test for your vitamin D 25-dihydroxy, also known as calcitriol, levels, simply put the test in your cart and check out online. Then, you can visit one of our 4,000 facilities to take the test. A member of our trained staff will collect a blood sample. Once you’ve given your sample, you’re done! In most cases, it will take just thirty minutes or so to complete your test and go on about your day.

When Do You Need a Vitamin D 25-Dihydroxy (Calcitriol) Test?

Your doctor may recommend a vitamin D 25-dihydroxy (calcitriol) test if you have signs of sarcoidosis, hypocalcemia or hypercalcemia, or kidney issues. Signs may include:

  • Chest pain, dry cough, or wheezing related to sarcoidosis
  • Stomach upset, nausea, vomiting, or constipation related to hypercalcemia
  • Problems like muscle cramps, muscle spasms, numbness, or seizures that could indicate hypocalcemia

You may also want to have a vitamin D 25-dihydroxy (calcitriol) test if your doctor has recommended it to check for potential signs of kidney problems. This test is less common than a full vitamin D test, which generally checks for vitamin D2, absorbed from your food. 

How to Interpret Your Results

We aim to make it as easy as possible to take a look at the results of your vitamin D 25-dihydroxy (calcitriol) test. When you receive your test results, you will notice three columns. The “reference range” column will give you the appropriate range for your calcitriol levels, which can help you understand where your results fall within those levels. The “results” column will detail your specific levels and test result. Finally, the “flag” column will help lay out whether your results are normal or abnormal. You may need a physician to help further interpret your test results or to help identify your next steps. 

Vitamin D 25-Dihydroxy (Calcitriol) Test vs. Vitamin D Panel

The vitamin D 25-dihydroxy (calcitriol) test is specifically intended to measure the levels of calcitriol in your blood and checks for vitamin D3, which is absorbed from sunlight, not vitamin D2, which is typically absorbed from food. While it can provide a measure for those specific results, this test is not intended to indicate overall vitamin D deficiency. If you have signs of overall vitamin D deficiency, including ongoing fatigue, achiness, depression, hair loss, or getting sick more easily, you may want to have a full vitamin panel or a vitamin D panel to check your overall levels.


  • The vitamin D 25-dihydroxy (calcitriol) test is designed primarily to test your calcitriol levels, not the overall vitamin D in your body. As a result, you may need to use a full vitamin D panel to test your comprehensive vitamin D levels.

  • If you need help interpreting the results of your test or more information about those direct results, our care counselors can assist you. If you require additional medical treatment or medical attention, you will need to consult with a physician. We can put you in contact with a physician if you need help finding someone to handle your care. 

  • The vitamin D 25-dihydroxy (calcitriol) test is generally recommend for people who may be showing signs of serious illness, including hypercalcemia, hypocalcemia, or kidney issues. You will generally take this test at your physician’s recommendation, or if you have questions about your overall health.