Vitamin D (25-OH): What It Measures

25-hydroxy vitamin D is the most common marker of vitamin D status. Learn what the value reflects and typical interpretation bands.

25-hydroxy vitamin D is the most widely used laboratory marker of vitamin D status. It reflects both dietary intake and skin-derived vitamin D.

Typical interpretation bands

• Deficient: less than 20 ng/mL
• Insufficient: 20–29 ng/mL
• Sufficient: 30–100 ng/mL

Why levels may be low

Limited sun exposure, certain diets, malabsorption, and some medications may all contribute to lower vitamin D.

Related guidance

For a more detailed walkthrough, see Normal Vitamin D Range.