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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 absorb calcium and maintain strong bones. Low levels may indicate deficiency, while high levels could signal overabsorption or certain conditions.

Quick summary

["Vitamin D levels help prevent bone-related issues and support overall health."]

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

Key facts at a glance

LOINC
109993-6
Short code
JCV IgG Msmt Ser
Synonyms
JCV 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 for vitamin D deficiency, which can lead to weak bones (osteomalacia or rickets in children), muscle pain, or other health problems. It may also be used to monitor vitamin D levels if you take supplements or have conditions like kidney disease or liver disease that affect vitamin D metabolism.

What to Expect Before the Test

No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before the draw if your lab uses a specific method for measuring vitamin D. Bring your test results from previous tests if you have them.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a small pinch, but it usually doesn’t cause discomfort. The blood sample is sent to a lab for analysis.

What Are the Possible Results?

Results are reported as a concentration of vitamin D in the blood (typically in nanograms per milliliter, ng/mL). Your provider will interpret the results based on your health status and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Vitamin D Levels Matter

Short name

Vitamin D level

Frequently asked questions

What Are Common Causes of Low Vitamin D?
Low vitamin D levels can be caused by limited sun exposure, certain medical conditions (like celiac disease or Crohn’s disease), obesity, or medications that interfere with vitamin D absorption. Chronic kidney or liver disease may also reduce vitamin D levels.
What Are Common Causes of High Vitamin D?
High vitamin D levels can result from overuse of supplements, certain medications (like anticonvulsants), or conditions like vitamin D toxicity. Rarely, it may be due to overproduction in the body.
How Often Should I Get This Test?
Your provider will determine how often you need this test based on your health needs. People with vitamin D deficiency or risk factors (like limited sun exposure or certain medical conditions) may need testing more frequently.
  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