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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 helps your body absorb calcium and maintain strong bones. Low levels may indicate deficiency, which can affect muscle function, bone health, and overall immunity.

Quick summary

["Vitamin D levels help prevent deficiencies that could lead to health issues like bone weakness or immune problems."]

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

Key facts at a glance

LOINC
41155-3
Short code
CMV IgM Fld-aCnc
Synonyms
CMV IgM Fld-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 fatigue, muscle pain, or frequent infections. It’s also used to check for vitamin D deficiency in people with limited sun exposure, certain medical conditions, or those taking medications that reduce vitamin D levels.

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 lab requires it. Wear comfortable clothing and plan for the test to be done at a clinic or lab.

What Happens During the Test?

A healthcare professional will insert a small needle into your arm to draw blood. You may feel a brief pinch, but the process is quick. The blood sample is sent to a lab for analysis.

What Are the Results Meaning?

Results are compared to standard ranges, but your provider will interpret them based on your health history and symptoms. Low levels may prompt lifestyle changes, supplements, or further testing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Vitamin D deficiency can lead to weakened bones, muscle weakness, or increased infection risk. High levels may indicate over-supplementation or liver/kidney issues, so monitoring is important.

Short name

Vitamin D Level (25-OH Vitamin D)

Frequently asked questions

How long does it take to get my vitamin D test results?
Results typically arrive within 1–3 business days, depending on your lab. Follow-up with your provider to discuss findings and next steps.
Can I take vitamin D supplements before my test?
Avoid taking vitamin D supplements or high-dose multivitamins for at least 2 weeks before testing to get an accurate reading. Check with your provider first.
What if my vitamin D level is too low?
If low, your provider may recommend dietary changes (e.g., fortified foods, fatty fish), sunlight exposure, or supplements under medical supervision. Lifestyle adjustments and follow-up testing are key.
  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