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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 other health functions.

Quick summary

["Vitamin D levels help assess your risk for bone-related issues and overall health."]

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

Key facts at a glance

LOINC
22411-3
Short code
LCMV IgM Titr Ser
Synonyms
LCMV 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 doctor may order a vitamin D test to check if you have low levels, which can lead to conditions like osteoporosis, muscle weakness, or other health problems. It may also be used to monitor vitamin D status in people with certain medical conditions or those taking supplements.

What to Expect Before the Test

No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before the draw, but this depends on your doctor’s instructions. Bring any medications you’re taking to your appointment.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. The process is quick and usually painless. You may feel a slight pinch, but it won’t take long.

What Are the Possible Results?

Results are typically reported as a numerical value representing your vitamin D concentration in the blood. Your doctor will interpret these results in relation to your health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low vitamin D levels may indicate poor absorption of nutrients, increased risk of fractures, or related conditions like rickets (in children) or osteomalacia (softening of bones). Some studies also link low vitamin D to autoimmune diseases, infections, and other chronic health concerns. Your doctor may recommend lifestyle changes, dietary adjustments, or supplements if needed.

Short name

Vitamin D level

Frequently asked questions

How long does it take to get my vitamin D test results?
Results are usually available within 1–3 business days, depending on your lab and insurance. Follow-up with your doctor will help clarify any findings.
Can I eat or drink anything before my vitamin D blood test?
Most labs recommend fasting for 8–12 hours before the test, but always confirm with your healthcare provider. Avoid alcohol and excessive caffeine on the day of testing.
Will I need to take any supplements if my vitamin D level is low?
If your doctor finds low vitamin D, they may recommend oral supplements (like D3) or recommend sun exposure. Never start supplements without medical guidance to avoid overdosing.
  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