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Serum/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 conditions and overall health."]

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

Key facts at a glance

LOINC
109325-1
Short code
PUUV IgG Msmt Ser
Synonyms
PUUV IgG Msmt 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 to check if you have enough vitamin D, which is essential for bone health, immune function, and muscle movement. It’s often recommended for people who don’t get enough sunlight, have limited sun exposure, or have conditions that affect vitamin D absorption.

What to Expect Before the Test

No special preparation is needed. You may have a blood sample drawn from a vein in your arm. If you’re taking vitamin D supplements, check with your provider first to avoid interfering with test results.

What the Results Mean

Results are typically reported as a concentration of vitamin D in the blood. Lower levels may indicate deficiency, which can lead to health issues like bone weakness or fatigue. Higher levels might suggest over-supplementation or other underlying conditions.

Common Causes of Low or High Levels

Low vitamin D levels can result from limited sun exposure, certain medical conditions (like kidney or liver disease), or poor diet. High levels may be due to overuse of supplements or certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

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’s processing time. Follow-up with your provider if you have questions about the results.
Can I eat or drink anything before this test?
You can eat and drink normally before the test, but avoid taking vitamin D supplements unless your provider has instructed otherwise. Fasted tests are not required for this blood draw.
What if my vitamin D level is too low?
If your results show low vitamin D, your provider may recommend dietary changes, increased sun exposure, or supplements to help restore healthy levels. They’ll work with you to create a plan tailored to your 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