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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 for bone health, immune function, and muscle strength.

Quick summary

["Vitamin D helps maintain strong bones and supports overall health; low levels may indicate deficiency."]

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

Key facts at a glance

LOINC
47432-0
Short code
EBV VCA IgG Titr Fld
Synonyms
EBV VCA IgG Titr Fld
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
8
Ref high
61
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82977
SNOMED
3110003
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 this test if you have symptoms of vitamin D deficiency (like fatigue, bone pain, or frequent infections), a history of limited sun exposure, or conditions that affect vitamin D absorption (such as kidney disease or certain gut disorders). It’s also used to monitor vitamin D levels in people taking supplements.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. If you’re taking blood thinners, let your doctor know to avoid unnecessary bleeding.

What the Results Mean

Results help determine if your vitamin D levels are within a healthy range. Low levels may prompt lifestyle changes (like more sun exposure or dietary adjustments) or medical treatment, while very high levels may require monitoring.

Common Causes of Low or High Levels

Low vitamin D can result from insufficient sun exposure, poor diet, or medical conditions affecting absorption. High levels may occur from over-supplementation or certain medications.

Reference range

Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Vitamin D level

Frequently asked questions

How often should I get this test?
Your doctor will decide based on your health status, symptoms, and risk factors. Typically, adults with no known deficiency may get it every 1–2 years, while those at higher risk (e.g., elderly, malabsorption disorders) may need more frequent checks.
What are the typical reference ranges?
Reference ranges vary by lab and may include categories like insufficient (<20 ng/mL), adequate (20–30 ng/mL), and sufficient (>30 ng/mL). Your results will be compared to your specific lab’s standards.
Can I take vitamin D supplements without checking my levels first?
It’s best to check your levels first, as high doses can be harmful. Always follow your doctor’s advice for supplementation.
  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