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Serum or Plasma Vitamin D (25-Hydroxyvitamin D) with Immunoassay

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 deficiencies that may affect bone health or other health conditions."]

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

Key facts at a glance

LOINC
85780-5
Short code
P aeruginosa DNA Bld Pos NAA+non-probe
Synonyms
P aeruginosa DNA Bld Pos NAA+non-probe
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
non-probe-amp-tar
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have symptoms of vitamin D deficiency—such as muscle weakness, bone pain, or frequent infections—or if you’re at higher risk, like having limited sun exposure, a diet low in vitamin D-rich foods, or certain medical conditions.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the blood draw if your lab requires it. Bring your test list and any medications you’re taking.

What the Test Results Mean

Low levels may indicate a deficiency, while higher levels could suggest over-supplementation or other metabolic factors. Your doctor will interpret results in relation to your overall health.

Common Causes of Abnormal Results

Deficiency can result from insufficient sun exposure, poor diet, malabsorption issues (like celiac disease), or certain medications. Overly high levels may occur with vitamin D supplements or rare genetic conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Vitamin D plays a critical role in bone mineralization, immune function, and cell growth. Deficiencies are linked to osteoporosis, muscle weakness, and increased infection risk, while excess can sometimes cause calcium-related complications.

Short name

Vitamin D Level

Frequently asked questions

How long does it take to get my results back?
Results are typically available within 1–3 business days, depending on your lab. Follow-up with your doctor to discuss findings and next steps.
What should I do if my vitamin D level is low?
Your doctor may recommend dietary changes (e.g., fatty fish, fortified foods) or supplements to raise levels safely. Avoid high-dose supplements without medical guidance.
Can I eat or drink anything before the blood test?
Check with your lab for fasting requirements, but generally, avoid caffeine or heavy meals 2 hours before the draw to ensure accurate results.
  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