Skip to content

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 use calcium and keep bones strong. Low levels may indicate vitamin D deficiency.

Quick summary

["Vitamin D levels help assess bone health and overall nutrient status."]

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

Key facts at a glance

LOINC
22605-0
Short code
VZV IgM Titr CSF
Synonyms
VZV IgM Titr CSF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Matters

Vitamin D is essential for bone health, immune function, and muscle strength. Your body produces some vitamin D when exposed to sunlight, but diet and supplements can also contribute. This test checks if your levels are within a healthy range.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before your blood is drawn. Wear a loose shirt for easy access. Your blood will be collected from a vein in your arm.

Common Causes of Low or High Levels

Low vitamin D levels may occur due to limited sun exposure, certain medical conditions (like malabsorption disorders), or medications. High levels can result from over-supplementation or rare genetic conditions.

What Your Results Mean

Results are typically reported as a numerical value (e.g., ng/mL or nmol/L), but your doctor will interpret them based on your health history and symptoms. Mild deficiencies may not cause symptoms, but severe deficiencies can lead to bone pain, fatigue, or muscle weakness.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

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. Follow up with your doctor to discuss your findings and any needed adjustments to diet or supplements.
Can I take vitamin D supplements before my test?
If you’re taking vitamin D supplements, your doctor may advise stopping them for a few days before testing to get an accurate measurement. Always check with your provider first.
What symptoms might indicate vitamin D deficiency?
Common symptoms include bone pain, muscle weakness, fatigue, or frequent infections. If you experience these, talk to your doctor about getting tested, especially if you have limited sun exposure or dietary restrictions.
  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