Vitamin D blood test
25-hydroxy vitamin D
In short
A typical adult vitamin D result is 30 to 100 ng/mL (some labs start at 20). A high vitamin D almost always comes from supplements. Very high levels can raise blood calcium, so doctors may check calcium too. Always read your result against the range printed on your own report.
The main blood test of the body's vitamin D supply.
Vitamin D helps the body absorb calcium and keep bones strong, and it comes from sunlight, food and supplements. This test measures 25-hydroxy vitamin D, the form in blood that best shows the body's supply. Experts disagree on the ideal level: some call 20 ng/mL (50 nmol/L) enough, others aim for 30 (75 nmol/L).
Is my Vitamin D high or low?
Type your result to see where it sits.
Nothing you type leaves this device.
Typical range
| For | Range | Unit |
|---|---|---|
| Adults · some labs start at 20 | 30–100 | ng/mL |
| Adults · some labs start at 50 | 75–250 | nmol/L |
Typical ranges for adults. Labs differ a little, so the range printed next to your result is the one to go by.
If your Vitamin D is high
A high vitamin D almost always comes from supplements. Very high levels can raise blood calcium, so doctors may check calcium too.
Common reasons
- Vitamin D supplements, especially high-dose ones
- Taking several products that each contain vitamin D
- High-dose vitamin D prescribed after a past low result
If your Vitamin D is low
Below 20 ng/mL (50 nmol/L), most experts agree vitamin D is low. Between 20 and 30 (50 to 75 nmol/L), experts disagree about whether it is too low.
Common reasons
- Little time in the sun, especially in winter or far from the equator
- Darker skin, which makes less vitamin D from the same sunlight
- Few vitamin D foods, such as oily fish or milk with added vitamin D
- Older age, as skin makes less vitamin D over time
- Higher body weight, since body fat holds on to vitamin D
- Some seizure medicines and steroid medicines
- Less often: gut, liver or kidney conditions that affect absorption or use
What can throw it off
Levels are usually lowest in late winter and highest in late summer, and recent supplements raise them.
Questions to take to your appointment
- 1Is my level low enough to matter for my bones?
- 2Should my calcium or parathyroid hormone be checked too?
- 3When would it make sense to recheck it?
Read together with
Doctors rarely read Vitamin D alone. These usually sit next to it.
Quick answers
What is the vitamin D blood test?
Vitamin D: The main blood test of the body's vitamin D supply. Vitamin D helps the body absorb calcium and keep bones strong, and it comes from sunlight, food and supplements. This test measures 25-hydroxy vitamin D, the form in blood that best shows the body's supply. Experts disagree on the ideal level: some call 20 ng/mL (50 nmol/L) enough, others aim for 30 (75 nmol/L).
What is a normal vitamin D level?
For most adults, vitamin D is typically 30 to 100 ng/mL (some labs start at 20). Some countries print it in nmol/L, so check the unit first. Labs differ a little, so the range printed next to your result is the one to go by.
What does a high vitamin D mean?
A high vitamin D almost always comes from supplements. Very high levels can raise blood calcium, so doctors may check calcium too. Common reasons include vitamin D supplements, especially high-dose ones; taking several products that each contain vitamin D; and high-dose vitamin D prescribed after a past low result. A doctor reads it together with your other results and how you feel.
What does a low vitamin D mean?
Below 20 ng/mL (50 nmol/L), most experts agree vitamin D is low. Between 20 and 30 (50 to 75 nmol/L), experts disagree about whether it is too low. Common reasons include little time in the sun, especially in winter or far from the equator; darker skin, which makes less vitamin D from the same sunlight; few vitamin D foods, such as oily fish or milk with added vitamin D; and older age, as skin makes less vitamin D over time.
What can affect my vitamin D result?
Levels are usually lowest in late winter and highest in late summer, and recent supplements raise them.
What should I ask my doctor about my vitamin D?
Questions worth taking to the appointment: Is my level low enough to matter for my bones? Should my calcium or parathyroid hormone be checked too? When would it make sense to recheck it?
What this page can’t do
It reads each number on its own.
Doctors read results together — ALT with AST, ferritin with hemoglobin, TSH with free T4. A pattern says more than any single flag.
It doesn't know you.
Your age, your medicines, how you feel and your last result all change what a number means.
It doesn't remember.
Close this page and your results are gone. That's on purpose: nothing was ever sent to us.
We also make Vita: Health Coach, an app for those parts. It reads your whole report with your medicines and history in mind, answers follow-up questions in plain words, and keeps your reports in one place — for you and for the people you look after.
Vita: Health Coach on the App StoreSources
- MedlinePlus — 25-hydroxy vitamin D test
- Merck Manual Professional — Vitamin D deficiency and dependency
- Labcorp — Vitamin D, 25-hydroxy (test 081950)
Stuck on a word? See the medical words. How we choose our sources. More about Vita Health Coach.