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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 levels help ensure your body has enough of this essential nutrient."]

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

Key facts at a glance

LOINC
104431-2
Short code
MuV IgM Ser+CSF-aCnc
Synonyms
MuV IgM Ser+CSF-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 if you have symptoms like muscle weakness, bone pain, or if you’re at risk for vitamin D deficiency, such as not getting enough sunlight or having limited sun exposure. It’s also used to monitor vitamin D levels in people taking supplements or those with conditions affecting vitamin D metabolism.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves a blood draw. 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. The blood sample is then sent to a lab for analysis. The test typically takes a few minutes, and you may feel slight discomfort but no lasting effects.

What Are the Results Mean?

Results are reported as a mass concentration of vitamin D in the blood, measured in nanograms per milliliter (ng/mL). Lower levels may indicate deficiency, while higher levels could suggest excess intake or certain medical conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Vitamin D Level (25-OH Vitamin D)

Frequently asked questions

What Are Common Questions About This Test?
Is fasting required for this test? Some tests may require fasting, but vitamin D tests often do not. Always follow your provider’s instructions.
How long does it take to get my results? Results are usually available within a few days to a week, depending on your lab and provider.
Can I take vitamin D supplements if my levels are low? If your levels are low, your provider may recommend supplements or dietary changes to help raise them safely.
What if my results are outside the normal range? If your results are low, you may need to increase vitamin D intake or take supplements under medical supervision. If high, discuss with your provider to determine the cause.
Does this test check for vitamin D binding protein? This test specifically measures free (unbound) vitamin D levels; binding protein levels are not assessed here.
  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