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Vitamin D, 25-Hydroxy [Mass Concentration]

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of vitamin D in your blood, which helps your body use calcium and maintain strong bones.

Quick summary

["Vitamin D levels help assess bone health and overall nutrient status."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
54351-2
Short code
Vit C+DHA SerPl-mCnc
Synonyms
Vit C+DHA SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test if you have symptoms like muscle weakness, bone pain, or if you’re at risk for vitamin D deficiency, such as living far from the equator, having limited sun exposure, or having certain medical conditions.

What to Expect Before the Test

No special preparation is needed. You may have a blood draw from a vein in your arm, similar to other blood tests. Wear a loose shirt for easy access.

What the Results Mean

Results are typically reported in units of mass concentration (nanograms per milliliter, ng/mL). Low levels may indicate deficiency, while higher levels may suggest overabsorption or certain conditions.

Common Conditions Linked to Vitamin D Levels

Low levels can contribute to conditions like osteoporosis, rickets (in children), or muscle weakness. High levels may be linked to kidney disease or over-supplementation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: Vitamin D is essential for bone mineralization, immune function, and cell growth. Abnormal levels can impact overall health and may require dietary adjustments, supplements, or medical treatment.

Short name

Vitamin D Level

Frequently asked questions

What causes vitamin D deficiency?
Deficiency can result from limited sun exposure, poor diet (low intake of fatty fish, fortified foods), certain medications, or conditions like malabsorption (e.g., celiac disease, Crohn’s).
How long does it take to get results?
Results are usually available within 1–3 business days, depending on your lab. Follow-up with your provider if you have questions about your results.
Can I take vitamin D supplements to raise my levels?
Yes, but always consult your healthcare provider first. They can guide dosage based on your test results and overall health to avoid excess.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

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 16, 2026. · Read our editorial policy