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Vitamin D (25-OH) blood test: what your result means
25-OH vitamin D measures the main circulating form of vitamin D and reflects overall vitamin D status.
- Category
- Vitamins
- Standard unit
- nmol/L
- Also called
- vitamin_d
- Reported in
- nmol/L, ng/mL, µg/L, µg/dL, µg/100mL, µg%
What does high vitamin D (25-OH) mean?
Higher values may suggest high supplementation or excess vitamin D exposure. What counts as high depends on the reference range printed on your lab report, because ranges differ between laboratories.
What does low vitamin D (25-OH) mean?
Lower values may suggest low vitamin D availability. What counts as low depends on the reference range printed on your lab report, because ranges differ between laboratories.
Vitamin D (25-OH) units and conversion
Mediki shows vitamin D (25-OH) in nmol/L. Labs may report it in other units; Mediki converts them automatically so results from different labs line up on one chart.
| Unit on your report | Convert to nmol/L | Convert back |
|---|---|---|
| ng/mL, µg/L | 1 ng/mL = 2.496 nmol/L | 1 nmol/L = 0.4006 ng/mL |
| µg/dL, µg/100mL, µg% | 1 µg/dL = 24.94 nmol/L | 1 nmol/L = 0.0401 µg/dL |
Convert a value from your report with the blood test unit converter.
Why track vitamin D (25-OH) over time?
A single vitamin D (25-OH) result is a snapshot. Comparing it with your earlier tests shows whether a value is stable, slowly drifting, or responding to a change in treatment or lifestyle, which is often more useful than one number on its own.
Read our guide on how to read blood test results to understand reference ranges, flags and units.
Following vitamin D (25-OH) as part of a panel? See the vitamin D and B12 tracker.
Track your vitamin D (25-OH) results in one chart
Upload your lab reports and Mediki plots every vitamin D (25-OH) result against its reference range. Your first 15 pages are free.
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Medical disclaimer: This page is general information, not medical advice. Reference ranges differ between laboratories, and only a doctor can interpret your results in the context of your health.