The vitamin D test (more precisely, 25-OH vitamin D) shows whether your body has enough of this vitamin, which matters for bones, muscles and immunity. Here is the simple version.
| Category | Reference range |
|---|---|
| Severe deficiency | under 10 ng/mL |
| Deficiency | 10–20 ng/mL |
| Insufficiency | 20–30 ng/mL |
| Sufficient level | 30–100 ng/mL |
Some labs report the result in nmol/L (1 ng/mL ≈ 2.5 nmol/L). Go by the units and the reference range printed on your own lab report.
Your body makes most of its vitamin D in the skin when you are out in the sun, and gets some of it from food. The 25-OH vitamin D test is the most reliable way to see the store of vitamin D you have built up over the past few weeks.
Deficiency is very common, especially in autumn and winter, in people who spend little time outdoors, and in northern regions.
A low vitamin D result means deficiency or insufficiency. It can go on without any obvious symptoms, but over time it affects the bones, the muscles and how you feel in general.
A level that is too high is rare and usually comes from taking large doses of supplements. Too much vitamin D can be harmful (it raises calcium in the blood), which is why long courses of high doses are taken under the watch of blood tests.
Compare your number with the categories above and with the reference range on your report. A value below 30 ng/mL is a reason to talk with your doctor about topping up; below 20 is already deficiency. Above 100 is a reason to revisit the dose of your supplements.
The result is read together with how you feel and, if needed, alongside your calcium and parathyroid hormone levels.
No need to decode the numbers yourself: take a photo of the report and the app explains “Vitamin D” and the rest in plain words — what is normal and what deserves attention.
Get the appOpen in TelegramA range of roughly 30–60 ng/mL is usually considered sufficient, but your doctor sets the target individually. Go by the reference range from your own lab.
No strict preparation is normally required, though many labs ask you to come in the morning on an empty stomach. Check the rules at your lab.
Preventive doses are often safe, but with a marked deficiency, or for treatment doses, it is better to know your starting level and stay under a doctor’s care so you do not end up with too much.
This material is for general information only. It is not a medical opinion and does not replace a consultation with a doctor. Reference ranges depend on the laboratory and the method — rely on the range printed on your own report. Your doctor makes the final interpretation. This page is a translation of the Russian original. The medical review applies to the original text.
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