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Serum or plasma 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 bone health. Low levels may indicate deficiency, which can affect muscle function, bone strength, and overall health.

Quick summary

["Vitamin D levels help assess bone health and prevent deficiencies that may cause weakness or other symptoms."]

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

Key facts at a glance

LOINC
42953-0
Short code
SSHV IgM Titr Ser
Synonyms
SSHV IgM Titr Ser
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 pain, fatigue, or bone pain, or if you’re at risk for vitamin D deficiency (e.g., limited sun exposure, certain diets, or conditions like obesity or kidney disease). It’s also used to monitor vitamin D levels in people taking supplements.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your lab uses a specific method. Bring your test list and any medications you’re currently taking.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually takes only a few minutes. The blood is sent to a lab for analysis.

What Are the Results?

Results are typically reported as a concentration of vitamin D in the blood, measured in nanograms per milliliter (ng/mL) or picomoles per liter (pmol/L). Your provider will interpret the results based on your health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

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 or fortified foods), obesity, certain medications, or conditions like kidney disease or malabsorption disorders.
How long does it take to get results?
Results are usually available within 1–3 business days, depending on your lab’s processing time. Your provider will contact you once they’re ready for review.
Can I take vitamin D supplements before the test?
Yes, but avoid taking large doses unless directed by your provider. If you’re on supplements, check with your healthcare team to ensure timing aligns with your test needs.
  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