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25-Hydroxy Vitamin D

Published: July 27, 2026Updated: August 25, 2026

This biomarker measures the level of 25-hydroxy vitamin D in the blood, which reflects the body's vitamin D stores and is crucial for bone health and calcium metabolism.

Quick summary

25-Hydroxy vitamin D levels indicate the body's vitamin D status and are essential for bone health.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
ng/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche Vitamin D, Abbott Vitamin D, Siemens Vitamin D, DiaSorin Vitamin D
interpretation: {"text":"Levels below 20 ng/mL may indicate vitamin D deficiency, requiring supplementation and further evaluation.","label":"Deficient"}; {"text":"Levels between 20–50 ng/mL are generally considered optimal for bone health and overall wellbeing.","label":"Optimal"}

25-Hydroxy vitamin D is the major circulating form of vitamin D and is used to assess vitamin D deficiency or excess. It is converted from vitamin D3 in the liver and serves as a precursor to the active form of vitamin D.

The reference range for 25-hydroxy vitamin D is typically between 20–50 ng/mL. Levels below 20 ng/mL are often considered indicative of vitamin D deficiency, which can lead to conditions such as rickets in children and osteomalacia in adults.

Monitoring 25-hydroxy vitamin D levels is important for individuals at risk of deficiency, including those with limited sun exposure, malabsorption disorders, or certain dietary restrictions. Supplementation may be recommended based on test results.

Frequently asked questions

What are the symptoms of vitamin D deficiency?
Symptoms may include fatigue, bone pain, muscle weakness, and increased risk of fractures.
How can I increase my vitamin D levels?
You can increase vitamin D levels through sun exposure, diet, and supplementation as advised by a healthcare provider.
  1. 1
    Vitamin D DeficiencySource
  2. 2
    25-Hydroxy Vitamin D TestSource

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy