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Serum or plasma concentration of vitamin D (25-hydroxyvitamin D)

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

This test measures your body’s level of vitamin D, an important nutrient that helps your bones stay strong and supports overall health.

Quick summary

["Vitamin D helps prevent bone-related issues and supports immune function."]

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

Key facts at a glance

LOINC
105904-7
Short code
VRE Spec Ql
Synonyms
VRE Spec Ql
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 to check if you have vitamin D deficiency, which can lead to weak bones, muscle pain, or other health problems. It’s also used to monitor vitamin D levels in people with conditions like osteoporosis, kidney disease, or those who don’t get enough sunlight.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the blood draw if your test uses a fasting sample. Bring any medications you’re taking to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. It usually takes a few minutes, and you may feel a slight pinch. The blood is then sent to a lab for analysis.

What Are the Results?

Results are typically reported as a concentration of vitamin D in the blood, though exact values can vary by lab. Your provider will interpret the results based on your health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low vitamin D levels may indicate deficiency, which can weaken bones, increase infection risk, or worsen certain chronic conditions. High levels may also occur in rare cases, such as overuse of supplements or certain liver/kidney disorders. Regular monitoring helps manage vitamin D levels effectively.

Short name

Vitamin D Level

Frequently asked questions

What causes vitamin D deficiency?
Vitamin D deficiency can result from limited sun exposure, poor diet (low in fatty fish, fortified foods, or egg yolks), certain medications, or conditions that affect vitamin D absorption or metabolism.
How long does it take to get results?
Results are usually available within 1–3 business days, depending on your lab and healthcare provider’s workflow.
Can I take vitamin D supplements before the test?
Yes, but avoid taking large doses unless instructed by your provider. If you’re on supplements, check with your healthcare team to ensure your results reflect your true vitamin D status.
  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