Vitamin D
Also known as: 25-hydroxyvitamin D, 25-OH vitamin D, Vitamin D 25-hydroxy
Vitamin D is a nutrient that helps your body absorb calcium and supports bone health, among other roles. The common blood test measures 25-hydroxyvitamin D, considered a good indicator of your overall vitamin D status.
Why it's measured
Vitamin D is checked when looking at bone health or general nutritional status, or when a deficiency is suspected. Levels can be influenced by sun exposure, diet, and the season.
Typical range
Labs often report vitamin D in ng/mL and may flag values below a certain threshold as low. Cut-offs differ between labs and guidelines, so your doctor interprets your result in context.
What high values can mean
Higher vitamin D is sometimes seen with supplementation. Very high levels are occasionally discussed in more detail by your doctor.
What low values can mean
Lower vitamin D is common, especially in winter or with limited sun exposure. Your doctor can explain whether your level warrants any follow-up or simple changes.
Questions to ask your doctor
- Is my vitamin D level something we should address?
- Could the season or my sun exposure have affected this?
- Should this be rechecked later in the year?
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Try the explainerEducational information only — not medical advice, diagnosis, or treatment. Reference ranges vary by lab; always use your own lab's range and discuss results with a qualified clinician.