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

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

This test measures the amount of vitamin D in your blood, which is important for bone health and other bodily functions.

Quick summary

["Vitamin D helps maintain strong bones and supports immune function."]

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

Key facts at a glance

LOINC
31495-5
Short code
LCMV IgM Ser-aCnc
Synonyms
LCMV IgM Ser-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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 enough vitamin D, which can be low due to limited sun exposure, certain medical conditions, or poor diet. It’s also used to monitor vitamin D levels in people taking supplements or those at risk of deficiency.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s a fasting sample. Wear comfortable clothing for drawing blood.

What Happens During the Test?

A healthcare professional will insert a small needle into your arm to draw blood. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood is then sent to a lab for analysis.

What Are the Possible Results?

Results are typically reported in nanograms per milliliter (ng/mL) or picomoles per liter (pmol/L). Your results will be compared to standard reference ranges provided by your lab.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low vitamin D levels may lead to weakened bones, increased risk of fractures, or weakened immunity. High levels can sometimes cause nausea, fatigue, or kidney issues. Your provider will interpret results in the context of your health and symptoms.

Short name

Vitamin D Level

Frequently asked questions

What causes vitamin D deficiency?
Vitamin D deficiency can result from limited sun exposure, certain skin conditions (like dark skin), obesity, malabsorption issues (e.g., celiac disease), or long-term use of certain medications. Lifestyle factors, such as avoiding fatty fish or fortified foods, can also contribute.
How long does it take to get results?
Results are usually available within 1–3 business days, depending on your lab and healthcare provider. Follow-up may be scheduled if further testing or adjustments are needed.
Can I take vitamin D supplements without checking my levels first?
It’s best to check your vitamin D levels before taking supplements. High doses can be harmful, and your provider can guide you on appropriate intake based on your results.
  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