| Marker | Gabriel optimal | Typical lab range | Functional range |
|---|---|---|---|
| Vitamin D, 25-OH | 50 to 75 ng/mL | 30 to 100 | 40 to 60 |
What the test measures
Your liver turns vitamin D from sun and food into 25-hydroxy vitamin D, written 25(OH)D. It is the best blood measure of whether you have enough. Results come in ng/mL or nmol/L (multiply ng/mL by 2.5 to get nmol/L).
A different test, 1,25-dihydroxy vitamin D, measures the active hormone. It is used mainly for kidney problems or unusual calcium levels, not to check your stores. More on the marker in Gabriel's vitamin D lab guide.
Deficient, insufficient, enough and too high
| 25(OH)D level | What sources say |
|---|---|
| Below 12 to 20 ng/mL (30 to 50 nmol/L) | Too low for bone and overall health |
| 20 ng/mL (50 nmol/L) or more | Enough for most people (NIH-based guidance) |
| 30 to 80 ng/mL (75 to 200 nmol/L) | The range many experts recommend (MedlinePlus) |
| Above 50 ng/mL (125 nmol/L) | Probably too high, per NIH-based guidance |
Gabriel's optimal band (50 to 75 ng/mL) follows the targets many functional clinicians use. It sits above the level some official guidance calls possibly too high, so don't chase a higher number with large doses unless a clinician is following your levels and your calcium.
What causes low vitamin D, and who should test
- Little sun on the skin, darker skin, or always using high-SPF sunscreen.
- Low intake. Fatty fish, egg yolks, UV-exposed mushrooms and fortified milk and cereals are the main food sources.
- Poor absorption, from conditions that affect fat absorption or weight-loss surgery.
- Liver or kidney disease.
- Medicines such as phenytoin, phenobarbital and rifampin.
Routine testing is not recommended for everyone. Clinicians usually test when there are bone problems (low bone density, fractures, bone pain, muscle weakness), a high risk of deficiency, or to follow up on supplements.
When vitamin D is too high
High levels (hypervitaminosis D) are almost always from supplements. Too much vitamin D raises blood calcium, which over time can harm the kidneys, bones and soft tissues. The adult upper limit is 4,000 IU a day from all sources; toxicity is unlikely below about 10,000 IU a day.
Contact a clinician if you take vitamin D and develop nausea or vomiting, poor appetite, constipation, strong thirst, frequent urination, confusion or muscle weakness. Those can be signs of high calcium.
Retesting after a change
- Ask when to recheck. Your clinician can time a retest so it reflects the change you made.
- Tell your clinician everything you take, including multivitamins and combination products that contain vitamin D.
- Use the same lab if you can, since methods and ranges vary between labs.
Common questions
What vitamin D level is deficient?
Most guidance calls levels below about 12 to 20 ng/mL (30 to 50 nmol/L) too low for bone and overall health. Your lab may flag anything under 30 ng/mL as insufficient.
What is a good vitamin D level?
Experts disagree. NIH-based guidance says 20 ng/mL or more is enough for most people, MedlinePlus notes many experts recommend 30 to 80 ng/mL, and Gabriel's optimal band is 50 to 75 ng/mL.
Can vitamin D be too high?
Yes. Above about 50 ng/mL may be too high according to NIH-based guidance, and very high levels raise blood calcium. It almost always comes from taking too much in supplements.
Do I need to fast for a vitamin D test?
Usually not, but follow any instructions from your lab. Tell your clinician about all vitamins and supplements you take.
How much does a vitamin D test cost?
It depends on the lab and your coverage. At Gabriel, a free account pays cost-plus prices on lab tests, and Core and Plus members get member prices; see how much a lab test costs.
Sources
- Vitamin D Test MedlinePlus, U.S. National Library of Medicine
- 25-hydroxy vitamin D test MedlinePlus, U.S. National Library of Medicine
- Vitamin D MedlinePlus, U.S. National Library of Medicine
- Hypervitaminosis D MedlinePlus, U.S. National Library of Medicine
This guide is general information, not medical advice. It does not replace a visit with a licensed clinician. Gabriel membership is not health insurance.