Skip to content

Serum Vitamin D (25-Hydroxyvitamin D) by Immunoassay

Published: August 9, 2026Updated: August 16, 2026

This test measures your levels of vitamin D in your blood, which is important for bone health and overall immune function.

Quick summary

["Vitamin D helps maintain strong bones and supports immune system health."]

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

Key facts at a glance

LOINC
22377-6
Short code
LASV IgG Ser Ql
Synonyms
LASV IgG Ser Ql
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 if you have symptoms of low vitamin D, such as muscle weakness, bone pain, or frequent illnesses. It may also be used to monitor vitamin D levels if you take supplements or have conditions that affect vitamin D absorption, like celiac disease or Crohn’s disease.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, and you’ll rest for a few minutes afterward. If you’re taking vitamin D supplements, let your provider know, as this may affect your results.

What the Results Mean

Vitamin D levels can vary based on factors like sunlight exposure, diet, and genetics. Your results will be compared to standard ranges to determine if your levels are low, normal, or high. Low levels may indicate a need for supplements or lifestyle changes.

Common Causes of Abnormal Results

Low vitamin D levels can be caused by limited sun exposure, poor diet, certain medical conditions, or medications that interfere with vitamin D production. High levels may result from overuse of supplements or certain liver/kidney disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Vitamin D Level

Frequently asked questions

What Are Normal Vitamin D Levels?
Normal vitamin D levels are typically measured in nanograms per milliliter (ng/mL) or nanomoles per liter (nmol/L). Your provider will interpret your results based on these standards and your overall health.
How Long Does It Take to Get Results?
Results are usually available within 1 to 3 business days, depending on your lab’s processing time. Follow up with your healthcare provider if you have questions about your results.
Can Vitamin D Levels Change Over Time?
Yes, vitamin D levels can fluctuate due to changes in sun exposure, diet, or health conditions. Regular monitoring may be recommended if you have ongoing concerns or take supplements.
  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