Information about a laboratory test
High 25(OH)D can reflect high-dose supplement exposure; very high concentrations may be associated with adverse effects.
The 25-Hydroxyvitamin D test measures vitamin D status and calcium-phosphate/bone metabolism.
Ordered when inadequate intake or absorption is suspected, in risk groups, or to assess supplement use; it is interpreted with related laboratory tests.
Low 25(OH)D is interpreted in the context of vitamin D inadequacy or deficiency. Calcium, phosphate, PTH, kidney function and clinical context matter.
High 25(OH)D can reflect high-dose supplement exposure; very high concentrations may be associated with adverse effects.
Start with the performing laboratory's reference interval, unit, specimen type and method. Numeric information on this page is stored as sourced example intervals or clinical thresholds.
< 12 ng/mL
25(OH)D concentration associated with vitamin D deficiency risk
This is a sourced clinical-context threshold and should not be used alone as a diagnosis or treatment decision. The laboratory report and clinical context take priority.
>= 12 – < 20 ng/mL
25(OH)D range generally considered inadequate
This is a sourced clinical-context threshold and should not be used alone as a diagnosis or treatment decision. The laboratory report and clinical context take priority.
>= 20 – <= 50 ng/mL
25(OH)D range generally adequate for most healthy people
This is a sourced clinical-context threshold and should not be used alone as a diagnosis or treatment decision. The laboratory report and clinical context take priority.
> 50 ng/mL
25(OH)D concentration associated with potential adverse effects
This is a sourced clinical-context threshold and should not be used alone as a diagnosis or treatment decision. The laboratory report and clinical context take priority.
Reference ranges may vary by laboratory, method used, age, sex, pregnancy status, and clinical context. The reference range on your own laboratory report takes precedence.
25(OH)D is the main laboratory indicator of vitamin D status. 1,25(OH)2D is not used for the same routine purpose.
Vitamin D – Health Professional Fact Sheet — NIH Office of Dietary Supplements
U.S. government nutrition reference · 2025 · 25(OH)D as vitamin D status marker and FNB concentration categories · Verified: Aug 12, 2026
Vitamin D Test — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2024 · 25-hydroxyvitamin D testing and distinction from active vitamin D · Verified: Aug 12, 2026
Calcium Blood Test — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2025 · Total calcium purpose, albumin context and example adult reference interval · Verified: Aug 12, 2026
Phosphate in Blood — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2023 · Phosphate interpretation with calcium, PTH, vitamin D and kidney function · Verified: Aug 12, 2026
Parathyroid Hormone (PTH) Test — U.S. National Library of Medicine (MedlinePlus)
Government medical reference · 2023 · PTH interpretation with calcium · Verified: Aug 12, 2026
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